Global gridded crop models(GGCMs) have been broadly applied to assess the impacts of climate and environmental change and adaptation on agricultural production. China is a major grain producing country, but thus far o...Global gridded crop models(GGCMs) have been broadly applied to assess the impacts of climate and environmental change and adaptation on agricultural production. China is a major grain producing country, but thus far only a few studies have assessed the performance of GGCMs in China, and these studies mainly focused on the average and interannual variability of national and regional yields. Here, a systematic national-and provincial-scale evaluation of the simulations by13 GGCMs [12 from the GGCM Intercomparison(GGCMI) project, phase 1, and CLM5-crop] of the yields of four crops(wheat, maize, rice, and soybean) in China during 1980–2009 was carried out through comparison with crop yield statistics collected from the National Bureau of Statistics of China. Results showed that GGCMI models generally underestimate the national yield of rice but overestimate it for the other three crops, while CLM5-crop can reproduce the national yields of wheat, maize, and rice well. Most GGCMs struggle to simulate the spatial patterns of crop yields. In terms of temporal variability, GGCMI models generally fail to capture the observed significant increases, but some can skillfully simulate the interannual variability. Conversely, CLM5-crop can represent the increases in wheat, maize, and rice, but works less well in simulating the interannual variability. At least one model can skillfully reproduce the temporal variability of yields in the top-10 producing provinces in China, albeit with a few exceptions. This study, for the first time, provides a complete picture of GGCM performance in China, which is important for GGCM development and understanding the reliability and uncertainty of national-and provincial-scale crop yield prediction in China.展开更多
In agriculture sector, machine learning has been widely used by researchers for crop yield prediction. However, it is quite difficult to identify the most critical features from a dataset. Feature selection techniques...In agriculture sector, machine learning has been widely used by researchers for crop yield prediction. However, it is quite difficult to identify the most critical features from a dataset. Feature selection techniques allow us to remove the extraneous and noisy features from the original feature set. The feature selection techniques help the model to focus only on the important features of the data, thus reducing execution time and improving efficiency of the model. The aim of this study is to determine relevant subset features for achieving high predictive performance by using different feature selection techniques like Filter methods, Wrapper methods and embedded methods. In this work, different feature selection techniques like Rank-based feature selection technique, weighted feature selection technique and Hybrid Feature Selection Technique have been applied to the agricultural data. The optimal feature set returned by different feature selection techniques is used for yield prediction using Linear regression, Random Forest, and Decision Tree Regressor. The accuracy of prediction obtained using the above three methods has been analyzed by using different evaluation parameters. This study helps in increasing predictive accuracy with the minimum number of features.展开更多
Ammonia (NH_3) emissions should be mitigated to improve environmental quality.Croplands are one of the largest NH_3sources,they must be managed properly to reduce their emissions while achieving the target yields.Here...Ammonia (NH_3) emissions should be mitigated to improve environmental quality.Croplands are one of the largest NH_3sources,they must be managed properly to reduce their emissions while achieving the target yields.Herein,we report the NH_3 emissions,crop yield and changes in soil fertility in a long-term trial with various fertilization regimes,to explore whether NH_3 emissions can be significantly reduced using the 4R nutrient stewardship (4Rs),and its interaction with the organic amendments (i.e.,manure and straw) in a wheat–maize rotation.Implementing the 4Rs significantly reduced NH_3 emissions to 6 kg N ha~(–1) yr~(–1) and the emission factor to 1.72%,without compromising grain yield (12.37 Mg ha~(–1) yr~(–1))and soil fertility (soil organic carbon of 7.58 g kg~(–1)) compared to the conventional chemical N management.When using the 4R plus manure,NH_3 emissions (7 kg N ha~(–1) yr~(–1)) and the emission factor (1.74%) were as low as 4Rs,and grain yield and soil organic carbon increased to 14.79 Mg ha~(–1) yr~(–1) and 10.09 g kg~(–1),respectively.Partial manure substitution not only significantly reduced NH_3 emissions but also increased crop yields and improved soil fertility,compared to conventional chemical N management.Straw return exerted a minor effect on NH_3 emissions.These results highlight that 4R plus manure,which couples nitrogen and carbon management can help achieve both high yields and low environmental costs.展开更多
Plastic film mulch in agricultural production becomes essential to maintaining crop yields in arid and semiarid areas.However,the presence of residual film in farmland soil has also drawn much attention.In this study,...Plastic film mulch in agricultural production becomes essential to maintaining crop yields in arid and semiarid areas.However,the presence of residual film in farmland soil has also drawn much attention.In this study,three experiments were conducted.The first two experimental designs included 0,450,1350,and 2700 kg ha^(-1) of residual film pieces of approximately 5 cm side length added to field soil(0-20 cm soil depth)for seven years and added to pots for four years.In the third experiment,1350 kg ha^(-1)of the residual film with different side lengths(2-5,5-10,10-15,and 15-20 cm)was added to field soil for six years to explore the effect of residual film fragment size on soil nutrients,soil microorganisms,crop growth and yields.The residual film had little effect on the soil moisture at a field depth of 0-2(or 0-1.8)m.There were no significant effects on organic carbon,total nitrogen,inorganic nitrogen,total phosphorus or available phosphorus in the 0-20 cm soil layer.The presence of residual film decreased the richness and diversity of the bacterial community of the surface soil of the residual film,but it had no significant effect on the microbial community of the non-surface soil.The emergence rates of wheat and lentils occasionally decreased significantly with different amounts of residue fragments added to the field.At 450-2700 kg ha^(-1),the residual film reduced the plant height and stem diameter of maize and significantly reduced the shoot biomass of harvested maize by 11-19%.The average yields of maize and potato over the seven years decreased,but there were almost no significant statistical differences among the treatments.These results provide important data for a comprehensive scientific understanding of the effects of residual film on soil and crops in dryland farming systems.展开更多
Salicylic acid(SA)is an effective elicitor to promote plant defenses and growth.This study aimed to investigate rice(Oryza sativa L.)cv.Khao Dawk Mali 105 treated with salicylic acid(SA)-Ricemate as an enhanced plant ...Salicylic acid(SA)is an effective elicitor to promote plant defenses and growth.This study aimed to investigate rice(Oryza sativa L.)cv.Khao Dawk Mali 105 treated with salicylic acid(SA)-Ricemate as an enhanced plant protection mechanism against bacterial leaf blight(BLB)disease caused by Xanthomonas oryzae pv.oryzae(Xoo).Results indicated that the use of SA-Ricemate as a foliar spray at concentrations of more than 100 mg L^(-1)can reduce the severity of BLB disease by 71%.SA-Ricemate treatment also increased the hydrogen peroxide(H_(2)O_(2))content of rice leaf tissues over untreated samples by 39–61%.Malondialdehyde(MDA)in rice leaves treated with SA-Ricemate also showed an increase of 50–65%when comparing to non-treated samples.The differential development of these defense compounds was faster and distinct when the SA-Ricemate-treated rice was infected with Xoo,indicating plant-induced resistance.Besides,SA-Ricemate elicitor at a concentration of 50–250 mg L^(-1)was correlated with a substantial increase in the accumulation of total chlorophyll content at 2.53–2.73 mg g^(-1)of fresh weight which suggests that plant growth is activated by SA-Ricemate.The catalase-and aldehyde dehydrogenase-binding sites were searched for using the CASTp server,and the findings were compared to the template.Chemsketch was used to design and optimize SA,which was then docked to the catalase and aldehyde dehydrogenase-binding domains of the enzymes using the GOLD 3.0.1 Software.SA is shown in several docked conformations with the enzymes catalase and aldehyde dehydrogenase.All three catalase amino acids(GLN7,VAL27,and GLU38)were discovered to be involved in the creation of a strong hydrogen bond with SA when SA was present.In this mechanism,the aldehyde dehydrogenase amino acids LYS5,HIS6,and ASP2 were all implicated,and these amino acids created strong hydrogen bonds with SA.In field conditions,SA-Ricemate significantly reduced disease severity by 78%and the total grain yield was significantly increased which was an increase of plant height,tiller per hill,and panicle in three field trials during Aug–Nov 2017 and 2018.Therefore,SA-Ricemate can be used as an alternative elicitor on replacing harmful pesticides to control BLB disease with a high potential of increasing rice defenses,growth,and yield components.展开更多
Crop Yield Prediction(CYP)is critical to world food production.Food safety is a top priority for policymakers.They rely on reliable CYP to make import and export decisions that must be fulfilled before launching an ag...Crop Yield Prediction(CYP)is critical to world food production.Food safety is a top priority for policymakers.They rely on reliable CYP to make import and export decisions that must be fulfilled before launching an agricultural business.Crop Yield(CY)is a complex variable influenced by multiple factors,including genotype,environment,and their interactions.CYP is a significant agrarian issue.However,CYP is the main task due to many composite factors,such as climatic conditions and soil characteristics.Machine Learning(ML)is a powerful tool for supporting CYP decisions,including decision support on which crops to grow in a specific season.Generally,Artificial Neural Networks(ANN)are usually used to predict the behaviour of complex non-linear models.As a result,this research paper attempts to determine the correlations between climatic variables,soil nutrients,and CYwith the available data.InANN,threemethods,Levenberg-Marquardt(LM),Bayesian regularisation(BR),and scaled conjugate gradient(SCG),are used to train the neural network(NN)model and then compared to determine prediction accuracy.The performance measures of the training,as declared above,such as Mean Squared Error(MSE)and correlation coefficient(R),were determined to assess the ANN models that had been built.The experimental study proves that LM training algorithms are better,while BR and SCG have minimal performance.展开更多
[Objective] Long-term （over 18 years） fertilization experiments were con- ducted to study the responses of crop yields and soil fertility to long-term nutrient lacking at Zhengzhou in China. [Method] The present stu...[Objective] Long-term （over 18 years） fertilization experiments were con- ducted to study the responses of crop yields and soil fertility to long-term nutrient lacking at Zhengzhou in China. [Method] The present study consisted of five treat- ments： 1 CK （no fertilizer or manure）, （2） NP （nitrogen and phosphorus fertilizer applied）, 31 NK （nitrogen and potassium fertilizer applied）, 4 PK （phosphorus and potassium fertilizer applied） and ：5 NPK （nitrogen, phosphorus and potassium fertil- izer applied）. [Result] Lacking of nitrogen or phosphorus led to a low yield; however, there was no significant difference in grain yields between the NP and NPK treat- ments which maintained a higher yield. Receiving no phosphorus, soil available phosphorus content declined to about 2.5 mg/kg. The concentration of soil ex- changeable potassium remained constant at a level of 60 mg/kg under the treat- ments without potassium fertilizer addition. Soil potassium spontaneous supply ca- pacity fluctuated around 100%.[Conclusion] In fluvo-aquic soil, nitrogen and phos- phorus were two key limiting factors to grain yields, biomass and yield component factors of wheat and maize, while potassium was not. However, potassium defi- ciency may occur in the future if there was still no potassium fertilizer applied.展开更多
It remains unclear whether biochar applications to calcareous soils can improve soil fertility and crop yield. A long-term field experiment was established in 2009 so as to determine the effect of biochar on crop yiel...It remains unclear whether biochar applications to calcareous soils can improve soil fertility and crop yield. A long-term field experiment was established in 2009 so as to determine the effect of biochar on crop yield and soil properties in a calcareous soil. Five treatments were： 1） straw incorporation; 2） straw incorporation with inorganic fertilizer; 3）, 4） and 5） straw incorporation with inorganic fertilizer, and biochar at 30, 60, and 90 t ha-l, respectively. The annual yield of either winter wheat or summer maize was not increased significantly following biochar application, whereas the cumulative yield over the first 4 growing seasons was significantly increased. Soil pH, measured in situ, was increased by a maximum of 0.35 units after 2 yr following biochar application. After 3 yr, soil bulk density significantly decreased while soil water holding capacity increased with adding biochar of 90 t ha^-1. Alkaline hydrolysable N decreased but exchangeable K increased due to biochar addition. Olsen-P did not change compared to the treatment without biochar. The results suggested that biochar could be used in calcareous soils without yield loss or significant impacts on nutrient availability.展开更多
Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The experiments on long-term application of K fertiliz...Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The experiments on long-term application of K fertilizer and wheat straw to soil in Hebei fluvo aquic soil and Shanxi brown soil in northern China were begun in 1992. The results showed that K fertilizer and straw could improve the yields of wheat and maize with the order of NPK ＋ St 〉 NPK 〉 NP ＋ St 〉 NP, and treatment of K fertilizer made a significant difference to NP, and the efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei. In contrast with Shanxi, the wastage of soil potassium was a more serious issue in the rotation system in Hebei, only treatment of NPK ＋ St showed a surplus of potassium and the others showed a wane. K fertilizer and straw could improve the content of water-soluble K, nonspecifically adsorbed K, non-exchangeable K, mineral K, and total K in contrast to NP; however, K fertilizer and straw reduce the proportion of mineral K and improve proportion of other forms of potassium in the two locating sites. Compared with the beginning of orientation, temporal variability character of soil K content and proportion showed a difference between the two soil types; furthermore, there was a decrease in the content of mineral K and total K simultaneously in the two locating sites. As a whole, the effect of K fertilizer applied to soil directly excelled to wheat straw to soil. Wheat straw to soil was an effective measure to complement potassium to increase crop yield and retard the decrease of soil K.展开更多
Significantly increasing temperature since the 1980s in China has become a consensus under the background of global climate change and how climate change affects agriculture or even cropping systems has attracted more...Significantly increasing temperature since the 1980s in China has become a consensus under the background of global climate change and how climate change affects agriculture or even cropping systems has attracted more and more attention from Chinese government and scientists. In this study, the possible effects of climate warming on the national northern limits of cropping systems, the northern limits of winter wheat and double rice, and the stable-yield northern limits of rainfed winter wheat-summer maize rotation in China from 1981 to 2007 were analyzed. Also, the possible change of crop yield caused by planting limits displacement during the periods 1950s-1981 and 1981-2007 was compared and discussed. The recognized calculation methods of agricultural climatic indices were employed. According to the indices of climatic regionalization for cropping systems, the national northern limits of cropping systems, winter wheat and double rice, and the stable-yield northern limits of rainfed winter wheat-summer maize rotation during two periods, including the 1950s-1980 and 1981-2007, were drawn with ArcGIS software. Compared with the situation during the 1950s- 1980, the northern limits of double cropping system during 1981-2007 showed significant spatial displacement in Shaanxi, Shanxi, Hebei, and Liaoning provinces and Beijing municipality, China. The northern limits of triple cropping system showed the maximum spatial displacement in Hunan, Hubei, Anhui, Jiangsu, and Zhejiang provinces, China. Without considering variety change and social economic factors, the per unit area grain yield of main planting patterns would increase about 54-106% if single cropping system was replaced by double cropping system, which turned out to be 27- 58% if double cropping system was replaced by triple cropping system. In Liaoning, Hebei, Shanxi, Shaanxi, Gansu, and Qinghai provinces, Inner Mongolia and Ningxia autonomous regions, China, the northern limits of winter wheat during 1981-2007 moved northward and expanded westward in different degrees, compared with those during the 1950s-1980. Taking Hebei Province as an example, the northern limits of winter wheat moved northward, and the per unit area grain yield would averagely increase about 25% in the change region if the spring wheat was replaced by winter wheat. In Zhejiang, Anhui, Hubei, and Hunan provinces, China, the planting northern limits of double rice moved northward, and the per unit area grain yield would increase in different degrees only from the perspective of heat resource. The stable- yield northern limits of rainfed winter wheat-summer maize rotation moved southeastward in most regions, which was caused by the decrease of local precipitation in recent years. During the past 50 yr, climate warming made the national northern limits of cropping systems move northward in different degrees, the northern limits of winter wheat and double rice both moved northward, and the cropping system change would cause the increase of per unit area grain yield in the change region. However, the stable-yield northern limits of rainfed winter wheat-summer maize rotation moved southeastward due to the decrease of precipitation.展开更多
A long term fertilization experiment was carried out in an experimental field in Lyczyn near Warsaw, Poland. Application ofmineral fertilizers, especially N fertilizers with and without farmyard manure accelerated th...A long term fertilization experiment was carried out in an experimental field in Lyczyn near Warsaw, Poland. Application ofmineral fertilizers, especially N fertilizers with and without farmyard manure accelerated the acidification process of the soil. Application of 1.6 t CaO ha -1 every four years was essential to maintenance of the soil pH KCl at 5.5～6.6 and base saturation degree above 60%. Application of 50 t farmyard manure ha -1 every 4 years, which contained 46 kg P and 240 kg K, was sufficient to maintain both the K and P fertility of the soil. Besides, it was beneficial to alleviating soil acidification. As a result of long term unbalanced fertilization, yield responses to N, P and K fertilizers increased significantly with time. The efficiency of N from farmyard manure was found to be comparable to that of N fertilizer during 1988～1991.展开更多
In this paper,spatial correlation of crop yield in the middle and west of Jilin Province is analyzed by us-ing the method of geostatistics semivariogram,taking the NDVI of NOAA/AVHRR spectrum data as the regionalized ...In this paper,spatial correlation of crop yield in the middle and west of Jilin Province is analyzed by us-ing the method of geostatistics semivariogram,taking the NDVI of NOAA/AVHRR spectrum data as the regionalized vari-able,aiming to provide theory and practical basis for field sampling of crop yield estimation using remote sensing.The ratio of nugget variance and sill of semivariograms are 21.1% and 9.7% in the west and middle regions in Jilin Province respectively.This shows that the crop yields are spatially correlated.The degree and range of correlation are far different in the different situations.In the west test region,the range is 49.9 km and the sill is 0.00019.In the middle testre-gion,the range is 16.5 km and the sill is0.00453.The dissimilarity in the western test region is larger than that in the middle one.The range in which the correlation existed of the former is far larger than the later.Different character is tics of spatial correlation of crop yield are decided by the environmental factors.Samples for crop yield estimation should be extracted according to the characteristic of spatial distribution of crop yield to promote the efficiency of sampling.展开更多
Preserving Tibet’s unique history and cultural heritage relies on the sustainability of the Tibetan croplands,which are characterized by highland barley,the only cereal crop cultivated over 4000 m above sea level.Yet...Preserving Tibet’s unique history and cultural heritage relies on the sustainability of the Tibetan croplands,which are characterized by highland barley,the only cereal crop cultivated over 4000 m above sea level.Yet it is unknown how these croplands will respond to climate change.Here,using yield statistics from 1985 to 2015,we found that the impact of temperature anomalies on the Tibetan crop yield shifted from nonsignificant(P>0.10)in the 1980s and 1990s to significantly negative(P<0.05)in recent years.Meanwhile,the apparent sensitivity of the crop yield to temperature anomalies almost doubled,from(–0.13±0.20)to(–0.22±0.14)t·ha^(-1)℃^(–1).The emerging negative impacts of higher temperatures suggest an increasing vulnerability of Tibetan croplands to warmer climate.With global warming scenarios of+1.5 or+2.0℃above the pre-industry level,the temperature sensitivities of crop yield may further increase to(–0.33±0.10)and(–0.51±0.18)t·ha^(-1)℃^(–1),respectively,making the crops 2–3 times more vulnerable to warmer temperatures than they are today.展开更多
The exponential growth of population in developing countries likeIndia should focus on innovative technologies in the Agricultural processto meet the future crisis. One of the vital tasks is the crop yield predictiona...The exponential growth of population in developing countries likeIndia should focus on innovative technologies in the Agricultural processto meet the future crisis. One of the vital tasks is the crop yield predictionat its early stage;because it forms one of the most challenging tasks inprecision agriculture as it demands a deep understanding of the growth patternwith the highly nonlinear parameters. Environmental parameters like rainfall,temperature, humidity, and management practices like fertilizers, pesticides,irrigation are very dynamic in approach and vary from field to field. In theproposed work, the data were collected from paddy fields of 28 districts in widespectrum of Tamilnadu over a period of 18 years. The Statistical model MultiLinear Regression was used as a benchmark for crop yield prediction, whichyielded an accuracy of 82% owing to its wide ranging input data. Therefore,machine learning models are developed to obtain improved accuracy, namelyBack Propagation Neural Network (BPNN), Support Vector Machine, andGeneral Regression Neural Networks with the given data set. Results showthat GRNN has greater accuracy of 97% (R2 = 0.97) with a normalizedmean square error (NMSE) of 0.03. Hence GRNN can be used for crop yieldprediction in diversified geographical fields.展开更多
Biochar(BC)is widely applied in agricultural production for its multiple uses such as carbon sequestration.However,application of BC alone has limited effect on soil fertility and crop yield,especially alkaline soil.T...Biochar(BC)is widely applied in agricultural production for its multiple uses such as carbon sequestration.However,application of BC alone has limited effect on soil fertility and crop yield,especially alkaline soil.Therefore,a pot experiment on Chinese cabbage(Brassica rapa var.glabra)was carried out in this study to investigate the effect of BC applied with organic fertilizer(OF)on alkaline soil properties and crop yield.To be specific,BC and OF were respectively applied at 0,1%,2%,and 3%,and Chinese cabbage was transplanted and cultivated for 2.5 months.Results showed that BC and OF increased the content of both organic matter and available P in alkaline soil(P<0.05).Moreover,the application of OF alone decreased the pH value but raised available N content of alkaline soil,and the application of only BC demonstrated the contrary effect(P<0.05).OF significantly improved crop yield(P<0.05),but the effect of BC was insignificant.Crop yield was the highest under the treatment of 1%BC and 3%OF.Thus,BC had limited effect on alkaline soil fertility and crop yield,but the application with OF was a good option for ameliorating alkaline soil and raising crop yield.展开更多
A field experiment was conducted to study the feasibility of irradiated and non-irradiated sewage sludge as a fertilizer for the growth of wheat and rice. The irradiated and non-irradiated sewage sludge were applied a...A field experiment was conducted to study the feasibility of irradiated and non-irradiated sewage sludge as a fertilizer for the growth of wheat and rice. The irradiated and non-irradiated sewage sludge were applied at rates of 0 (CK), 75, 150, 225 and 300 kg N ha-1 for wheat, and 0 (CK), 112.5, 225, 337.5 and 450 kg N ha-1 for rice, respectively. (NH4)2SO4 at a rate of 150 kg N ha-1 for wheat, and 225 kg N ha-1 for rice were added to the control treatments. Additionally, 20 kg 15N ha-1 in the form of (NH4)2SO4 was added to each treatment for wheat to study the effect of sewage sludge on chemical nitrogen fertilizer recovery. The results showed that the irradiation of sewage sludge by gamma ray at a dosage of 5 kGy increased crop yield by 11%～27% as compared to the non-irradiated treatments. Irradiation stimulated mineralization of organic nitrogen in the sludge and improved seedling growth. It was found that addition of irradiated sludge could reduce the leaching loss of chemical nitrogen fertilizer. Both irradiated and non-irradiated sewage sludge could increase the content of soil total nitrogen. Based on the preliminary results, it was concluded that irradiated sewage sludge could partly substitute for chemical nitrogen fertilizer in crop production.展开更多
Although wastewater irrigation in agriculture could be a potential adaptation to water scarcity, its effect on crop yield varies in the literature, making it difficult to evaluate its role in global food security comp...Although wastewater irrigation in agriculture could be a potential adaptation to water scarcity, its effect on crop yield varies in the literature, making it difficult to evaluate its role in global food security comprehensively. Using agronomic experiment data from 62 studies between 1987 and 2021, we employ a meta-analysis to analyze the factors contributing to the heterogeneous effects of wastewater irrigation on crop yield. Our findings can be summarized as(1) the mean yield growth effect of wastewater irrigation is 19.7%;(2) domestic and breeding wastewater irrigation could significantly increase crop yield, while industrial wastewater has a negative effect although not significant;(3) high nutrients concentration of domestic wastewater is significantly positively correlated with crop yield;(4) agronomic experiment designs in terms of field experiment, experiment times, and fertilizer use could contribute to the divergent crop yield effects across the studies;(5) there is a publication bias of the research results between the English and Chinese literature;(6) the literature mainly sheds light on the short-run effect, and the long-run impact shall be an important research question in the future.展开更多
Agricultural system is very complex since it deals with large data situation which comes from a number of factors. A lot of techniques and approaches have been used to identify any interactions between factors that af...Agricultural system is very complex since it deals with large data situation which comes from a number of factors. A lot of techniques and approaches have been used to identify any interactions between factors that affecting yields with the crop performances. The application of neural network to the task of solving non-linear and complex systems is promising. This paper presents a review on the use of artificial neural network （ANN） in predicting crop yield using various crop performance factors. General overview on the application of ANN and the basic concept of neural network architecture are also presented. From the literature, it has been shown that ANN provides better interpretation of crop variability compared to the other methods.展开更多
De-farming slope farmland has been an effective measure in recent years for the improvement of the eco-environment and the mitigation of soil and water loss on the Loess Plateau. This paper, taking the Yangou Basin as...De-farming slope farmland has been an effective measure in recent years for the improvement of the eco-environment and the mitigation of soil and water loss on the Loess Plateau. This paper, taking the Yangou Basin as a case study and using day-by-day mete- orological data of Yah＇an station in 2005, simulated and analyzed the quantitative relation between crop yield, soil and water loss and topographic condition with the aid of WIN-YIELD software. Results show that： 1） topographic gradient has important influence on crop yield. The bigger gradient is, the lower the crop yield. Yields of sorghum and corn decrease by 15.44% and 14.32% respectively at 25° in comparison to the case of 0°. In addition, yields of soya, bean and potato decrease slightly by 5.26%, 4.67% and 3.84%, respectively. The influences of topographic height and slope aspect on crop yield are slight. 2） Under the same topographic condition, different crops＇ runoff and soil loss show obvious disparity. Topographic gradient has important influence on soil and water loss. In general, the changing trend is that the soil and water loss aggregates with the increase of gradient, and the maximal amount occurs around 20°. The influence of topographic height is slight. Topographic aspect has a certain effect, and the fundamental characteristic is that values are higher at the aspect of south than north. 3） Topographic gradients of 5° and 15° are two important thresholds. The characteristic about soil and water loss with the variation of topographic gradients show that： the slope farmland with gradient less than 5° could remain unchanged, and the slope farmland more than 15° should be de-farmed as early as possible.展开更多
基金co-supported by the Guangdong Major Project of Basic and Applied Basic Research (Grant No. 2021B0301030007)the National Key Research and Development Program of China (Grant Nos. 2017YFA0604302 and 2017YFA0604804)+1 种基金the National Natural Science Foundation of China (Grant No. 41875137)the National Key Scientific and Technological Infrastructure project “Earth System Science Numerical Simulator Facility” (Earth Lab)。
文摘Global gridded crop models(GGCMs) have been broadly applied to assess the impacts of climate and environmental change and adaptation on agricultural production. China is a major grain producing country, but thus far only a few studies have assessed the performance of GGCMs in China, and these studies mainly focused on the average and interannual variability of national and regional yields. Here, a systematic national-and provincial-scale evaluation of the simulations by13 GGCMs [12 from the GGCM Intercomparison(GGCMI) project, phase 1, and CLM5-crop] of the yields of four crops(wheat, maize, rice, and soybean) in China during 1980–2009 was carried out through comparison with crop yield statistics collected from the National Bureau of Statistics of China. Results showed that GGCMI models generally underestimate the national yield of rice but overestimate it for the other three crops, while CLM5-crop can reproduce the national yields of wheat, maize, and rice well. Most GGCMs struggle to simulate the spatial patterns of crop yields. In terms of temporal variability, GGCMI models generally fail to capture the observed significant increases, but some can skillfully simulate the interannual variability. Conversely, CLM5-crop can represent the increases in wheat, maize, and rice, but works less well in simulating the interannual variability. At least one model can skillfully reproduce the temporal variability of yields in the top-10 producing provinces in China, albeit with a few exceptions. This study, for the first time, provides a complete picture of GGCM performance in China, which is important for GGCM development and understanding the reliability and uncertainty of national-and provincial-scale crop yield prediction in China.
文摘In agriculture sector, machine learning has been widely used by researchers for crop yield prediction. However, it is quite difficult to identify the most critical features from a dataset. Feature selection techniques allow us to remove the extraneous and noisy features from the original feature set. The feature selection techniques help the model to focus only on the important features of the data, thus reducing execution time and improving efficiency of the model. The aim of this study is to determine relevant subset features for achieving high predictive performance by using different feature selection techniques like Filter methods, Wrapper methods and embedded methods. In this work, different feature selection techniques like Rank-based feature selection technique, weighted feature selection technique and Hybrid Feature Selection Technique have been applied to the agricultural data. The optimal feature set returned by different feature selection techniques is used for yield prediction using Linear regression, Random Forest, and Decision Tree Regressor. The accuracy of prediction obtained using the above three methods has been analyzed by using different evaluation parameters. This study helps in increasing predictive accuracy with the minimum number of features.
基金supported by the Hainan Key Research and Development Project, China (ZDYF2021XDNY184)the Hainan Provincial Natural Science Foundation of China (422RC597)+2 种基金the National Natural Science Foundation of China (41830751)the Hainan Major Science and Technology Program, China (ZDKJ2021008)the Hainan University Startup Fund,China (KYQD(ZR)-20098)。
文摘Ammonia (NH_3) emissions should be mitigated to improve environmental quality.Croplands are one of the largest NH_3sources,they must be managed properly to reduce their emissions while achieving the target yields.Herein,we report the NH_3 emissions,crop yield and changes in soil fertility in a long-term trial with various fertilization regimes,to explore whether NH_3 emissions can be significantly reduced using the 4R nutrient stewardship (4Rs),and its interaction with the organic amendments (i.e.,manure and straw) in a wheat–maize rotation.Implementing the 4Rs significantly reduced NH_3 emissions to 6 kg N ha~(–1) yr~(–1) and the emission factor to 1.72%,without compromising grain yield (12.37 Mg ha~(–1) yr~(–1))and soil fertility (soil organic carbon of 7.58 g kg~(–1)) compared to the conventional chemical N management.When using the 4R plus manure,NH_3 emissions (7 kg N ha~(–1) yr~(–1)) and the emission factor (1.74%) were as low as 4Rs,and grain yield and soil organic carbon increased to 14.79 Mg ha~(–1) yr~(–1) and 10.09 g kg~(–1),respectively.Partial manure substitution not only significantly reduced NH_3 emissions but also increased crop yields and improved soil fertility,compared to conventional chemical N management.Straw return exerted a minor effect on NH_3 emissions.These results highlight that 4R plus manure,which couples nitrogen and carbon management can help achieve both high yields and low environmental costs.
基金funded by the National Natural Science Foundation of China (31470496)the Fundamental Research Funds for the Central Universities, China (lzujbky-2021-sp42)the ‘111’ Programme 2.0, China (BP0719040)。
文摘Plastic film mulch in agricultural production becomes essential to maintaining crop yields in arid and semiarid areas.However,the presence of residual film in farmland soil has also drawn much attention.In this study,three experiments were conducted.The first two experimental designs included 0,450,1350,and 2700 kg ha^(-1) of residual film pieces of approximately 5 cm side length added to field soil(0-20 cm soil depth)for seven years and added to pots for four years.In the third experiment,1350 kg ha^(-1)of the residual film with different side lengths(2-5,5-10,10-15,and 15-20 cm)was added to field soil for six years to explore the effect of residual film fragment size on soil nutrients,soil microorganisms,crop growth and yields.The residual film had little effect on the soil moisture at a field depth of 0-2(or 0-1.8)m.There were no significant effects on organic carbon,total nitrogen,inorganic nitrogen,total phosphorus or available phosphorus in the 0-20 cm soil layer.The presence of residual film decreased the richness and diversity of the bacterial community of the surface soil of the residual film,but it had no significant effect on the microbial community of the non-surface soil.The emergence rates of wheat and lentils occasionally decreased significantly with different amounts of residue fragments added to the field.At 450-2700 kg ha^(-1),the residual film reduced the plant height and stem diameter of maize and significantly reduced the shoot biomass of harvested maize by 11-19%.The average yields of maize and potato over the seven years decreased,but there were almost no significant statistical differences among the treatments.These results provide important data for a comprehensive scientific understanding of the effects of residual film on soil and crops in dryland farming systems.
基金supported by the Suranaree University of Technology,Thailand,the Thailand Science Research and Innovation(TSRI)the National Science,Research and Innovation Fund,Thailand(NSRF)(90464).
文摘Salicylic acid(SA)is an effective elicitor to promote plant defenses and growth.This study aimed to investigate rice(Oryza sativa L.)cv.Khao Dawk Mali 105 treated with salicylic acid(SA)-Ricemate as an enhanced plant protection mechanism against bacterial leaf blight(BLB)disease caused by Xanthomonas oryzae pv.oryzae(Xoo).Results indicated that the use of SA-Ricemate as a foliar spray at concentrations of more than 100 mg L^(-1)can reduce the severity of BLB disease by 71%.SA-Ricemate treatment also increased the hydrogen peroxide(H_(2)O_(2))content of rice leaf tissues over untreated samples by 39–61%.Malondialdehyde(MDA)in rice leaves treated with SA-Ricemate also showed an increase of 50–65%when comparing to non-treated samples.The differential development of these defense compounds was faster and distinct when the SA-Ricemate-treated rice was infected with Xoo,indicating plant-induced resistance.Besides,SA-Ricemate elicitor at a concentration of 50–250 mg L^(-1)was correlated with a substantial increase in the accumulation of total chlorophyll content at 2.53–2.73 mg g^(-1)of fresh weight which suggests that plant growth is activated by SA-Ricemate.The catalase-and aldehyde dehydrogenase-binding sites were searched for using the CASTp server,and the findings were compared to the template.Chemsketch was used to design and optimize SA,which was then docked to the catalase and aldehyde dehydrogenase-binding domains of the enzymes using the GOLD 3.0.1 Software.SA is shown in several docked conformations with the enzymes catalase and aldehyde dehydrogenase.All three catalase amino acids(GLN7,VAL27,and GLU38)were discovered to be involved in the creation of a strong hydrogen bond with SA when SA was present.In this mechanism,the aldehyde dehydrogenase amino acids LYS5,HIS6,and ASP2 were all implicated,and these amino acids created strong hydrogen bonds with SA.In field conditions,SA-Ricemate significantly reduced disease severity by 78%and the total grain yield was significantly increased which was an increase of plant height,tiller per hill,and panicle in three field trials during Aug–Nov 2017 and 2018.Therefore,SA-Ricemate can be used as an alternative elicitor on replacing harmful pesticides to control BLB disease with a high potential of increasing rice defenses,growth,and yield components.
文摘Crop Yield Prediction(CYP)is critical to world food production.Food safety is a top priority for policymakers.They rely on reliable CYP to make import and export decisions that must be fulfilled before launching an agricultural business.Crop Yield(CY)is a complex variable influenced by multiple factors,including genotype,environment,and their interactions.CYP is a significant agrarian issue.However,CYP is the main task due to many composite factors,such as climatic conditions and soil characteristics.Machine Learning(ML)is a powerful tool for supporting CYP decisions,including decision support on which crops to grow in a specific season.Generally,Artificial Neural Networks(ANN)are usually used to predict the behaviour of complex non-linear models.As a result,this research paper attempts to determine the correlations between climatic variables,soil nutrients,and CYwith the available data.InANN,threemethods,Levenberg-Marquardt(LM),Bayesian regularisation(BR),and scaled conjugate gradient(SCG),are used to train the neural network(NN)model and then compared to determine prediction accuracy.The performance measures of the training,as declared above,such as Mean Squared Error(MSE)and correlation coefficient(R),were determined to assess the ANN models that had been built.The experimental study proves that LM training algorithms are better,while BR and SCG have minimal performance.
基金Support by the Special Fund for Agro-scientific Research in the Public Interest of China(201203030-5)National Natural Science Foundation of China(41201288,41201255,31301284)+2 种基金Key Programs for Science and Technology Development of Henan Province(132102110068)Excellent Youth Science and Technology Foundation of Henan Academy of Agricultural Sciences(2013YQ15)JIRCAS-IARRP collaborative research:Estimation of the Present States of Fertilizer Use and Livestock Production and Their Environmental Load~~
文摘[Objective] Long-term （over 18 years） fertilization experiments were con- ducted to study the responses of crop yields and soil fertility to long-term nutrient lacking at Zhengzhou in China. [Method] The present study consisted of five treat- ments： 1 CK （no fertilizer or manure）, （2） NP （nitrogen and phosphorus fertilizer applied）, 31 NK （nitrogen and potassium fertilizer applied）, 4 PK （phosphorus and potassium fertilizer applied） and ：5 NPK （nitrogen, phosphorus and potassium fertil- izer applied）. [Result] Lacking of nitrogen or phosphorus led to a low yield; however, there was no significant difference in grain yields between the NP and NPK treat- ments which maintained a higher yield. Receiving no phosphorus, soil available phosphorus content declined to about 2.5 mg/kg. The concentration of soil ex- changeable potassium remained constant at a level of 60 mg/kg under the treat- ments without potassium fertilizer addition. Soil potassium spontaneous supply ca- pacity fluctuated around 100%.[Conclusion] In fluvo-aquic soil, nitrogen and phos- phorus were two key limiting factors to grain yields, biomass and yield component factors of wheat and maize, while potassium was not. However, potassium defi- ciency may occur in the future if there was still no potassium fertilizer applied.
基金financially supported by the National Natural Science Foundation of China (41171211)
文摘It remains unclear whether biochar applications to calcareous soils can improve soil fertility and crop yield. A long-term field experiment was established in 2009 so as to determine the effect of biochar on crop yield and soil properties in a calcareous soil. Five treatments were： 1） straw incorporation; 2） straw incorporation with inorganic fertilizer; 3）, 4） and 5） straw incorporation with inorganic fertilizer, and biochar at 30, 60, and 90 t ha-l, respectively. The annual yield of either winter wheat or summer maize was not increased significantly following biochar application, whereas the cumulative yield over the first 4 growing seasons was significantly increased. Soil pH, measured in situ, was increased by a maximum of 0.35 units after 2 yr following biochar application. After 3 yr, soil bulk density significantly decreased while soil water holding capacity increased with adding biochar of 90 t ha^-1. Alkaline hydrolysable N decreased but exchangeable K increased due to biochar addition. Olsen-P did not change compared to the treatment without biochar. The results suggested that biochar could be used in calcareous soils without yield loss or significant impacts on nutrient availability.
文摘Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The experiments on long-term application of K fertilizer and wheat straw to soil in Hebei fluvo aquic soil and Shanxi brown soil in northern China were begun in 1992. The results showed that K fertilizer and straw could improve the yields of wheat and maize with the order of NPK ＋ St 〉 NPK 〉 NP ＋ St 〉 NP, and treatment of K fertilizer made a significant difference to NP, and the efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei. In contrast with Shanxi, the wastage of soil potassium was a more serious issue in the rotation system in Hebei, only treatment of NPK ＋ St showed a surplus of potassium and the others showed a wane. K fertilizer and straw could improve the content of water-soluble K, nonspecifically adsorbed K, non-exchangeable K, mineral K, and total K in contrast to NP; however, K fertilizer and straw reduce the proportion of mineral K and improve proportion of other forms of potassium in the two locating sites. Compared with the beginning of orientation, temporal variability character of soil K content and proportion showed a difference between the two soil types; furthermore, there was a decrease in the content of mineral K and total K simultaneously in the two locating sites. As a whole, the effect of K fertilizer applied to soil directly excelled to wheat straw to soil. Wheat straw to soil was an effective measure to complement potassium to increase crop yield and retard the decrease of soil K.
基金funded by the Mode Construction of Modern Farming System and Supporting Technology Research and Demonstration, China (200803028)
文摘Significantly increasing temperature since the 1980s in China has become a consensus under the background of global climate change and how climate change affects agriculture or even cropping systems has attracted more and more attention from Chinese government and scientists. In this study, the possible effects of climate warming on the national northern limits of cropping systems, the northern limits of winter wheat and double rice, and the stable-yield northern limits of rainfed winter wheat-summer maize rotation in China from 1981 to 2007 were analyzed. Also, the possible change of crop yield caused by planting limits displacement during the periods 1950s-1981 and 1981-2007 was compared and discussed. The recognized calculation methods of agricultural climatic indices were employed. According to the indices of climatic regionalization for cropping systems, the national northern limits of cropping systems, winter wheat and double rice, and the stable-yield northern limits of rainfed winter wheat-summer maize rotation during two periods, including the 1950s-1980 and 1981-2007, were drawn with ArcGIS software. Compared with the situation during the 1950s- 1980, the northern limits of double cropping system during 1981-2007 showed significant spatial displacement in Shaanxi, Shanxi, Hebei, and Liaoning provinces and Beijing municipality, China. The northern limits of triple cropping system showed the maximum spatial displacement in Hunan, Hubei, Anhui, Jiangsu, and Zhejiang provinces, China. Without considering variety change and social economic factors, the per unit area grain yield of main planting patterns would increase about 54-106% if single cropping system was replaced by double cropping system, which turned out to be 27- 58% if double cropping system was replaced by triple cropping system. In Liaoning, Hebei, Shanxi, Shaanxi, Gansu, and Qinghai provinces, Inner Mongolia and Ningxia autonomous regions, China, the northern limits of winter wheat during 1981-2007 moved northward and expanded westward in different degrees, compared with those during the 1950s-1980. Taking Hebei Province as an example, the northern limits of winter wheat moved northward, and the per unit area grain yield would averagely increase about 25% in the change region if the spring wheat was replaced by winter wheat. In Zhejiang, Anhui, Hubei, and Hunan provinces, China, the planting northern limits of double rice moved northward, and the per unit area grain yield would increase in different degrees only from the perspective of heat resource. The stable- yield northern limits of rainfed winter wheat-summer maize rotation moved southeastward in most regions, which was caused by the decrease of local precipitation in recent years. During the past 50 yr, climate warming made the national northern limits of cropping systems move northward in different degrees, the northern limits of winter wheat and double rice both moved northward, and the cropping system change would cause the increase of per unit area grain yield in the change region. However, the stable-yield northern limits of rainfed winter wheat-summer maize rotation moved southeastward due to the decrease of precipitation.
文摘A long term fertilization experiment was carried out in an experimental field in Lyczyn near Warsaw, Poland. Application ofmineral fertilizers, especially N fertilizers with and without farmyard manure accelerated the acidification process of the soil. Application of 1.6 t CaO ha -1 every four years was essential to maintenance of the soil pH KCl at 5.5～6.6 and base saturation degree above 60%. Application of 50 t farmyard manure ha -1 every 4 years, which contained 46 kg P and 240 kg K, was sufficient to maintain both the K and P fertility of the soil. Besides, it was beneficial to alleviating soil acidification. As a result of long term unbalanced fertilization, yield responses to N, P and K fertilizers increased significantly with time. The efficiency of N from farmyard manure was found to be comparable to that of N fertilizer during 1988～1991.
文摘In this paper,spatial correlation of crop yield in the middle and west of Jilin Province is analyzed by us-ing the method of geostatistics semivariogram,taking the NDVI of NOAA/AVHRR spectrum data as the regionalized vari-able,aiming to provide theory and practical basis for field sampling of crop yield estimation using remote sensing.The ratio of nugget variance and sill of semivariograms are 21.1% and 9.7% in the west and middle regions in Jilin Province respectively.This shows that the crop yields are spatially correlated.The degree and range of correlation are far different in the different situations.In the west test region,the range is 49.9 km and the sill is 0.00019.In the middle testre-gion,the range is 16.5 km and the sill is0.00453.The dissimilarity in the western test region is larger than that in the middle one.The range in which the correlation existed of the former is far larger than the later.Different character is tics of spatial correlation of crop yield are decided by the environmental factors.Samples for crop yield estimation should be extracted according to the characteristic of spatial distribution of crop yield to promote the efficiency of sampling.
基金the Second Tibetan Plateau Scien-tific Expedition and Research Program(2019QZKK0405)the National Natural Science Foundation of China project Basic Science Center for Tibetan Plateau Earth System(41988101).
文摘Preserving Tibet’s unique history and cultural heritage relies on the sustainability of the Tibetan croplands,which are characterized by highland barley,the only cereal crop cultivated over 4000 m above sea level.Yet it is unknown how these croplands will respond to climate change.Here,using yield statistics from 1985 to 2015,we found that the impact of temperature anomalies on the Tibetan crop yield shifted from nonsignificant(P>0.10)in the 1980s and 1990s to significantly negative(P<0.05)in recent years.Meanwhile,the apparent sensitivity of the crop yield to temperature anomalies almost doubled,from(–0.13±0.20)to(–0.22±0.14)t·ha^(-1)℃^(–1).The emerging negative impacts of higher temperatures suggest an increasing vulnerability of Tibetan croplands to warmer climate.With global warming scenarios of+1.5 or+2.0℃above the pre-industry level,the temperature sensitivities of crop yield may further increase to(–0.33±0.10)and(–0.51±0.18)t·ha^(-1)℃^(–1),respectively,making the crops 2–3 times more vulnerable to warmer temperatures than they are today.
文摘The exponential growth of population in developing countries likeIndia should focus on innovative technologies in the Agricultural processto meet the future crisis. One of the vital tasks is the crop yield predictionat its early stage;because it forms one of the most challenging tasks inprecision agriculture as it demands a deep understanding of the growth patternwith the highly nonlinear parameters. Environmental parameters like rainfall,temperature, humidity, and management practices like fertilizers, pesticides,irrigation are very dynamic in approach and vary from field to field. In theproposed work, the data were collected from paddy fields of 28 districts in widespectrum of Tamilnadu over a period of 18 years. The Statistical model MultiLinear Regression was used as a benchmark for crop yield prediction, whichyielded an accuracy of 82% owing to its wide ranging input data. Therefore,machine learning models are developed to obtain improved accuracy, namelyBack Propagation Neural Network (BPNN), Support Vector Machine, andGeneral Regression Neural Networks with the given data set. Results showthat GRNN has greater accuracy of 97% (R2 = 0.97) with a normalizedmean square error (NMSE) of 0.03. Hence GRNN can be used for crop yieldprediction in diversified geographical fields.
文摘Biochar(BC)is widely applied in agricultural production for its multiple uses such as carbon sequestration.However,application of BC alone has limited effect on soil fertility and crop yield,especially alkaline soil.Therefore,a pot experiment on Chinese cabbage(Brassica rapa var.glabra)was carried out in this study to investigate the effect of BC applied with organic fertilizer(OF)on alkaline soil properties and crop yield.To be specific,BC and OF were respectively applied at 0,1%,2%,and 3%,and Chinese cabbage was transplanted and cultivated for 2.5 months.Results showed that BC and OF increased the content of both organic matter and available P in alkaline soil(P<0.05).Moreover,the application of OF alone decreased the pH value but raised available N content of alkaline soil,and the application of only BC demonstrated the contrary effect(P<0.05).OF significantly improved crop yield(P<0.05),but the effect of BC was insignificant.Crop yield was the highest under the treatment of 1%BC and 3%OF.Thus,BC had limited effect on alkaline soil fertility and crop yield,but the application with OF was a good option for ameliorating alkaline soil and raising crop yield.
文摘A field experiment was conducted to study the feasibility of irradiated and non-irradiated sewage sludge as a fertilizer for the growth of wheat and rice. The irradiated and non-irradiated sewage sludge were applied at rates of 0 (CK), 75, 150, 225 and 300 kg N ha-1 for wheat, and 0 (CK), 112.5, 225, 337.5 and 450 kg N ha-1 for rice, respectively. (NH4)2SO4 at a rate of 150 kg N ha-1 for wheat, and 225 kg N ha-1 for rice were added to the control treatments. Additionally, 20 kg 15N ha-1 in the form of (NH4)2SO4 was added to each treatment for wheat to study the effect of sewage sludge on chemical nitrogen fertilizer recovery. The results showed that the irradiation of sewage sludge by gamma ray at a dosage of 5 kGy increased crop yield by 11%～27% as compared to the non-irradiated treatments. Irradiation stimulated mineralization of organic nitrogen in the sludge and improved seedling growth. It was found that addition of irradiated sludge could reduce the leaching loss of chemical nitrogen fertilizer. Both irradiated and non-irradiated sewage sludge could increase the content of soil total nitrogen. Based on the preliminary results, it was concluded that irradiated sewage sludge could partly substitute for chemical nitrogen fertilizer in crop production.
基金supported by the National Social Science Fund of China(20CSH048,20AZD024 and 21ZDA062)the National Natural Science Foundation of China(71773099)+1 种基金the Humanities and Social Sciences Project Funded by the Ministry of Education,China(21YJC790110)the Rural Finance Survey of the Ministry of Agriculture and Rural Affairs,China(05190084)。
文摘Although wastewater irrigation in agriculture could be a potential adaptation to water scarcity, its effect on crop yield varies in the literature, making it difficult to evaluate its role in global food security comprehensively. Using agronomic experiment data from 62 studies between 1987 and 2021, we employ a meta-analysis to analyze the factors contributing to the heterogeneous effects of wastewater irrigation on crop yield. Our findings can be summarized as(1) the mean yield growth effect of wastewater irrigation is 19.7%;(2) domestic and breeding wastewater irrigation could significantly increase crop yield, while industrial wastewater has a negative effect although not significant;(3) high nutrients concentration of domestic wastewater is significantly positively correlated with crop yield;(4) agronomic experiment designs in terms of field experiment, experiment times, and fertilizer use could contribute to the divergent crop yield effects across the studies;(5) there is a publication bias of the research results between the English and Chinese literature;(6) the literature mainly sheds light on the short-run effect, and the long-run impact shall be an important research question in the future.
文摘Agricultural system is very complex since it deals with large data situation which comes from a number of factors. A lot of techniques and approaches have been used to identify any interactions between factors that affecting yields with the crop performances. The application of neural network to the task of solving non-linear and complex systems is promising. This paper presents a review on the use of artificial neural network （ANN） in predicting crop yield using various crop performance factors. General overview on the application of ANN and the basic concept of neural network architecture are also presented. From the literature, it has been shown that ANN provides better interpretation of crop variability compared to the other methods.
基金Knowledge Innovation Project of the Chinese Academy of Sciences,No.KZCX2-XB2-05-01National Natural Science Foundation of China,No.40771086
文摘De-farming slope farmland has been an effective measure in recent years for the improvement of the eco-environment and the mitigation of soil and water loss on the Loess Plateau. This paper, taking the Yangou Basin as a case study and using day-by-day mete- orological data of Yah＇an station in 2005, simulated and analyzed the quantitative relation between crop yield, soil and water loss and topographic condition with the aid of WIN-YIELD software. Results show that： 1） topographic gradient has important influence on crop yield. The bigger gradient is, the lower the crop yield. Yields of sorghum and corn decrease by 15.44% and 14.32% respectively at 25° in comparison to the case of 0°. In addition, yields of soya, bean and potato decrease slightly by 5.26%, 4.67% and 3.84%, respectively. The influences of topographic height and slope aspect on crop yield are slight. 2） Under the same topographic condition, different crops＇ runoff and soil loss show obvious disparity. Topographic gradient has important influence on soil and water loss. In general, the changing trend is that the soil and water loss aggregates with the increase of gradient, and the maximal amount occurs around 20°. The influence of topographic height is slight. Topographic aspect has a certain effect, and the fundamental characteristic is that values are higher at the aspect of south than north. 3） Topographic gradients of 5° and 15° are two important thresholds. The characteristic about soil and water loss with the variation of topographic gradients show that： the slope farmland with gradient less than 5° could remain unchanged, and the slope farmland more than 15° should be de-farmed as early as possible.
