Validating CERES-wheat under North-German environmental conditions

The predictive quality of CERES-wheat was tested under contrasting nitrogen management and temperate-maritime climate conditions of North-Germany. Field data from 9 years of observations were used in this study. The magnitudes of the genetic parameters of the local wheat cultivar “Orestis” were strongly influenced by seasonal weather fluctuations. For predicted yield and harvest biomass, the root mean square error was 2.2 t/ha and 3.2 t/ha, respectively. These errors were too large to permit a practical application of the CERES-wheat model for optimizing fertilizer management under the production conditions of North-Germany. The results of this study suggest that the model needs to be considerably improved with respect to the simulation of soil and plant water-relations, as well as the interaction between water and nitrogen uptake which were found to be inconsistent.     

水-氮联合限制条件下对水稻生产模型ORYZA2000的验证与评价

介绍了水稻生长模拟模型ORYZA2000,并应用2002年水肥耦合试验资料,在水氮联合限制条件下对水稻生产模型ORYZA2000进行了参数校正,对模拟效果进行了图解分析和回归分析,结果表明,在水分平衡和氮素平衡条件下,ORYZA2000模拟水稻生物量、产量、氮素平衡以及田间水分平衡是可行的。该模型在水稻节水灌溉领域有很大的应用价值,为我国水稻节水灌溉向数字化发展提供了有利工具。     

Evaluation of the VegSyst model with muskmelon to simulate crop growth, nitrogen uptake and evapotranspiration

Like many intensive vegetable production systems, the greenhouse-based system on the south-eastern (SE) Mediterranean coast of Spain is associated with considerable NO₃⁻ contamination of groundwater. Drip irrigation and sophisticated fertigation systems provide the technical capacity for precise nutrient and irrigation management of soil-grown crops which would reduce NO₃⁻ leaching loss. The VegSyst crop simulation model was developed to simulate daily crop biomass production, N uptake and crop evapotranspiration (ET_c). VegSyst is driven by thermal time and consequently is adaptable to different planting dates, different greenhouse cooling practices and differences in greenhouse design. It will be subsequently incorporated into a practical on-farm decision support system to enable growers to more effectively use the advanced technical capacity of this horticultural system for optimal N and irrigation management.VegSyst was calibrated and validated for muskmelon grown in Mediterranean plastic greenhouse in SE Spain using data of four melon crops, two grown in 2005 and two in 2006 using two management strategies of water and N management in each year. VegSyst very accurately simulated crop biomass production and accurately simulated crop N uptake over time. Model performance in simulating dry matter production (DMP) over time was better using a double radiation use efficiency (RUE) approach (5.0 and 3.2 g MJ⁻¹ PAR for vegetative and reproductive growth phases) compared to a single RUE approach (4.3 g MJ⁻¹ PAR). The simulation of ET_c over time, was very accurate in the two 2006 muskmelon crops and somewhat less so in the two 2005 crops. The error in the simulated final values, expressed as a percentage of final measured values was −1 to 6% for DMP, 2-11% for crop N uptake, and −11 to 6% for ET_c. VegSyst provided effective simulation of DMP, N uptake and ET_c for crops with different planting dates. This model can be readily adapted to other crops.     

Modelling of water and nitrogen balances in the ponded water and soil profile of rice fields in Northern Greece

This paper presents a water and nitrogen balance model for the surface ponded water and soil profile system of rice (Oryza sativa L.) fields. The model estimates the daily water balance components, as well as, the daily losses and transformations of nitrogen. Data from two neighbouring rice fields during the growing season of 2005 in the Thessaloniki plain of Northern Greece were used for the application of the model. The data set of field A was used for the calibration of the model, while the data set from the field B for validation of model. Simulation results of total inorganic nitrogen in the soil and runoff water exhibited reasonable agreement with the measured data during calibration and verification of the model. Significant amounts of applied irrigation water were lost through surface runoff and deep percolation into the groundwater. The sum of nitrogen inputs from fertilization, mineralization and irrigation water were 292.7 and 280.4 kg ha⁻¹ for field A and B, respectively. Nitrogen uptake by algae in ponding water and plants was one of the main processes of nitrogen reduction in the rice field systems with an amount of 125.7 and 131.8 kg ha⁻¹ for field A and B, respectively. Leaching through percolated water was the other significant process with 118.3 and 120.8 kg ha⁻¹, respectively. Gaseous losses of nitrogen (via volatilization and denitrification) were also substantial processes of nitrogen reduction in the flooded compartment. The study showed that the simple model presents important results for the water and nitrogen management in rice fields. This information can be used for irrigation water saving and prevention of water resources contamination in rice-based agroecosystems.     

Opportunities for yield increases and environmental benefits through site-specific nutrient management in rice systems of Zhejiang province,China

Environmental pollution by nitrogen (N) leaching or runoff from rice fields and high pesticide use has become a serious concern in China. Average N application is high and fertilizer-N use efficiency is low compared with other major rice growing countries. In Zhejiang, rice farmers apply 150–250 kg ha⁻¹ fertilizer N and 7–10 sprays of pesticides per season to maintain yield levels of 5.5–8.0 t ha⁻¹. Fertilizer and pest management strategies of farmers are not based on plant nutrient demand and pest control requirements. To provide farmers with options for high yielding, yet more resourceful management options, site-specific nutrient management (SSNM) was developed at Zhejiang University in collaboration with the International Rice Research Institute (IRRI). The approach comprises guidelines that allow farmers to adjust domain- and season-specific fertilizer recommendations to actual growing conditions in their fields taking into account plant nutrient demand, indigenous nutrient supply, nutrient use efficiency, as well as socio-economic factors. The main objective of this paper is to evaluate the agronomic performance of SSNM in farmers’ fields in the past seven years (1998–2004). With SSNM, average grain yield increased by about 0.5 t ha⁻¹ over the farmers’ practice, while N use efficiency increased significantly. About 30% of both fertilizer N could be reduced through adoption of SSNM, which would effectively eliminate an unnecessary source of pollution in the rice ecosystem. Larger scale dissemination of SSNM for rice is under way in Zhejiang province, but stronger institutional support is urgently required.     

Disentangling the effect of environmental factors on yield and nitrogen uptake of irrigated rice in Asia

Rice yield is the result of the interaction between genotype (cultivar characteristics), environment (climate and soil conditions), and management. Few studies have attempted to isolate the contribution of each of these factors. Here the rice growth model ORYZA2000 was used to analyse the variation in yield, nitrogen (N) uptake, and internal N use efficiency (INUE, grain yield per unit total crop N uptake) of rice in different environments. First, ORYZA2000 was calibrated and evaluated using an empirical data set that spanned three varieties, three years, and eight locations in Asia. Next, we used the model to investigate the relative contribution of indigenous soil N and external N supply and of the weather factors temperature and radiation to observed variation in yield.     

Yield, water and nitrogen-use response of rice to zeolite and nitrogen fertilization in a semi-arid environment

Water scarcity and soil nitrogen (N) loss are important limitations for agricultural production in semi-arid region especially for rice production. Zeolite (Z) as a soil conditioner can be used to retrain water and nitrogen in near-surface soil layer in lowland rice production system. The objectives of this study were to investigate the effects of different application rates of natural zeolite (clinoptilolite) and nitrogen on rice yield, yield components, soil nitrogen, water use, water productivity in a silty clay soil in 2004 and 2005. Zeolite was only applied in the first year. In order to study the long-term and continuous effect of zeolite on the objectives of the study, no zeolite was applied in the second year and the study was conducted on the same land as the first year. Zeolite and N were applied at rates of 0, 2, 4, and 8 t ha⁻¹ and 0, 20, 40, and 80 kg ha⁻¹, respectively in 2004. In 2005, each plot received the same amount of N as received in 2004. It is concluded that by decreasing N application rates, higher Z application rate is needed to improve grain yield. Highest grain yield was obtained at N application rate of 80 kg ha⁻¹ and Z application rate of 4 t ha⁻¹. Higher grain yield was mostly attributed to lower unfilled grain percentage and higher 1000-grain weight that were a result of higher N application rate and N retention in soil due to Z application. Nitrogen and Z applications resulted in higher grain protein contents and nitrogen recovery efficiency (NRE). Based on these results and due to higher N retention in soil under Z application, improved grain yield quality, nitrogen-use efficiency (NUE), and nitrogen recovery efficiency (NRE) could be obtained at Z application rate of 8 t ha⁻¹ and N application rate of 80 kg ha⁻¹ or more. However, this was not satisfied for NUE. Moreover, it is found that at higher N application rates lower Z application rates are needed to effectively retain soil residual mineral nitrogen. Furthermore, at N application rates of 80 kg ha⁻¹ or more, Z application increased soil water retention and resulted in lower seasonal water use and higher water productivity. In general, it was concluded that the effect of Z application in retaining soil N was also effective in the second year.     

控制灌溉条件下增氧对超级稻根系生长及水分利用效率的影响

以超级稻“陵两优268”为试验材料,采用控制灌溉与增氧灌溉技术相结合,设置4组处理,分别为机械控制灌溉增氧(JX)、超微泡控制灌溉增氧(WP)、控制灌溉(CK)、淹水灌溉(YS),研究控制灌溉条件下增氧对水稻根系生长特征及水分利用效率的影响.结果表明:控制灌溉条件下增氧与淹水灌溉条件相比,有效节约用水最大达15.3%,有利于促进根系生长,增大了水稻的根部干物质质量,降低了水稻的茎叶干物质质量;提高了水稻根体积、根粗及干物质的质量,能显著增强水稻的根系活力,延缓水稻根系的衰老;产量上,控制灌溉增氧处理基本与淹灌处理接近,但结实率、千粒重、水分利用效率都优于淹灌处理.     

Impact of water application conditions on nitrogen leaching under furrow irrigation: Experimental and modelling approaches

Local infiltration tests on 1.5 m long blocked furrows were carried out on a loam soil to assess N fertiliser leaching under furrow irrigation where ridging operations entails placing nitrogen on the upper part of the ridge. This article focuses on the impact of flow depths, or water application depth (WAD), on nitrogen movement in seven 1.5-m long blocked furrows. For a first irrigation event, a WAD greater than or equal to 240 mm, significantly reduced the heterogeneity of the N concentration profiles measured at the top of the ridge and beneath the furrow. The virtually homogeneous N soil distribution with depth permitted the determination of the nitrogen balance throughout the season using soil samples obtained at the beginning and end of the season as well as the determination of nitrogen present in the crop tissue. This is not possible when there is a heterogeneous N soil profile at the end of the irrigation season, as observed under moderate WAD conditions. In addition, a substantial WAD delivered during the first irrigation event, and at a period where the plant N requirements are high, does not affect crop yield potential.     

Maize yield response to deficit irrigation during low-sensitive growth stages and nitrogen rate under semi-arid climatic conditions

Knowledge of crop production in suboptimal environmental conditions not only helps to sustain crop production but also aids in the design of low-input systems. The objective of this study was to evaluate the effects of water stress imposed at low-sensitive growth stages (vegetative, reproductive, and both vegetative and reproductive) and level of nitrogen (N) supply (100 and 200 kg ha⁻¹) on the physiological and agronomic characteristics of two hybrids of maize (Zea mays L.). A two-site field experiment was carried out using a randomized complete block design with three replications and a split-factorial arrangement. A water deficit (WD) was induced by withholding irrigation at different stages of crop development. The results showed that proline content increased and the relative water content, leaf greenness, 100-kernel weight and grain yield decreased under conditions of WD. The highest IWUE was obtained when maize endured WD at vegetative stage at two sites. The limited irrigation imposed on maize during reproductive stage resulted in more yield reduction than that during vegetative stage, compared with fully irrigated treatment. The 100-kernel weight was the most sensitive yield component to determine the yield variation in maize plant when the WD treatments were imposed in low-sensitive growth stages. The results of the statistical regression analysis showed liner relationships between RGR during a period bracketing the V₈ or R₃ stages and 100-kernel weight in all the WD treatments. The increase of N supply improved yield and IWUE when maize plant endured once irrigation shortage at vegetative stage. But, the performance of high N fertilizer reduced and eliminated when water deficit imposed once at reproductive stage and twice at vegetative and reproductive stages, respectively. Furthermore, the response of T.C647 hybrid to increase of N supply was stronger than S.C647 hybrid.     

水稻新品种千乡优616和千优531高产栽培模式初探

稻水稻良种良法配套作为我国水稻产量提高的重要经验和法宝在水稻产量增长中发挥重要作用。2022年四川省内江市农业科学院利用联合选育的高产水稻品种千乡优616、千优531,开展人工移栽、机械移栽（机插秧）和直播三种不同栽培模式对比试验,对品种不同栽培模式的优劣性、适应性、经济性进行分析,找出适合品种自身的高产稳产种植模式,为千乡优616、千优531的推广应用提供参考。     

InfoCrop: A dynamic simulation model for the assessment of crop yields,losses due to pests,and environmental impact of agro-ecosystems in tropical environments. II. Performance of the model

InfoCrop, a generic crop model, simulates the effects of weather, soils, agronomic management (planting, nitrogen, residues and irrigation) and major pests on crop growth, yield, soil carbon, nitrogen and water, and greenhouse gas emissions. This paper presents results of its evaluation in terms of its validation for rice and wheat crops in contrasting agro-environments of tropics, sensitivity to the key inputs, and also illustrates two typical applications of the model. Eleven diverse field experiments, having treatments of location, seasons, varieties, nitrogen management, organic matter, irrigation, and multiple pest incidences were used for validation. Grain yields in these experiments varied from 2.8 to 7.2 ton ha⁻¹ in rice and from 3.6 to 5.5 ton ha⁻¹ in wheat. The results indicated that the model was generally able to explain the differences in biomass, grain yield, emissions of carbon dioxide, methane and nitrous oxides, and long-term trends in soil organic carbon, in diverse agro-environments. The losses in dry matter and grain yield due to different pests and their populations were also explained satisfactorily. There were some discrepancies in the simulated emission of these gases during first few days after sowing/transplanting possibly because of the absence of tillage effects in the model. The sensitivity of the model to change in ambient temperature, crop duration and pest incidence was similar to the available field knowledge. The application of the model to quantify multiple pests damage through iso-loss curves is demonstrated. Another application illustrated is the use of InfoCrop for analyzing the trade-offs between increasing crop production, agronomic management strategies, and their global warming potential.     

Ammonium enhances the tolerance of rice seedlings (Oryza sativa L.) to drought condition

In order to study the effects of different nitrogen (N) forms on drought tolerance of rice seedlings, both hydroponic and pot experiments were conducted in green house. In hydroponic experiments, water stress was simulated by treatment with polyethylene glycol (PEG, 10% in w/v, MW6000); in pot experiments, rice seedlings were cultivated under non-flooded conditions. The results showed that: (1) under water stress conditions, the decrease in plant growth and photosynthesis under ammonium supply was less than under nitrate supply; (2) under non-flooded cultivation, the biomass and photosynthesis in rice plants supplied with ammonium and ammonium + dicyandiamide (DCD, a nitrification inhibitor) were higher than those in nitrate fertilization; (3) in hydroponic experiments, water uptake of rice seedlings under ammonium nutrition was higher than under nitrate nutrition. It is concluded that, ammonium nutrition can enhance the tolerance of rice plants to water stress.     

混合动力推土机建模与全工况经济性仿真

为了对履带式混合动力推土机在全工况下的经济性进行仿真分析,对ADVISOR进行二次开发,在Matlab/Simulink环境下建立直驶和转向动力学模型、履带行走机构模型、油泵模型和分动箱模型等,进而构建了混合动力推土机及其对照机的整机仿真模型。分别对两对照机进行实机试验,并对比仿真与试验中的关键运行参数以验证模型精度。结果表明,所建立模型在全工况下具有较高的仿真精度。利用该模型进行的全工况经济性仿真分析显示,混合动力推土机在直行推土和转向中均具有显著的节能效果,采用发动机-发电机组最优效率曲线控制时节能效果得到进一步提升。     

Evaluation on the irrigation and fertilization management practices under the application of treated sewage water in Beijing, China

Irrigation and fertilization management practices play important roles in crop production. In this paper, the Root Zone Water Quality Model (RZWQM) was used to evaluate the irrigation and fertilization management practices for a winter wheat–summer corn double cropping system in Beijing, China under the irrigation with treated sewage water (TSW). A carefully designed experiment was carried out at an experimental station in Beijing area from 2001 to 2003 with four irrigation treatments. The hydrologic, nitrogen and crop growth components of RZWQM were calibrated by using the dataset of one treatment. The datasets of other three treatments were used to validate the model performance. Most predicted soil water contents were within ±1 standard deviation (S.D.) of the measured data. The relative errors (RE) of grain yield predictions were within the range of −26.8% to 18.5%, whereas the REs of biomass predictions were between −38% and 14%. The grain nitrogen (N) uptake and biomass N uptake were predicted with the RE values ranging from −13.9% to 14.7%, and from −11.1% to 29.8%, respectively. These results showed that the model was able to simulate the double cropping system variables under different irrigation and fertilization conditions with reasonable accuracy. Application of RZWQM in the growing season of 2001–2002 indicated that the best irrigation management practice was no irrigation for summer corn, three 83 mm irrigations each for pre-sowing, jointing and heading stages of winter wheat, respectively. And the best nitrogen application management practice was 120 kg N ha⁻¹ for summer corn and 110 kg N ha⁻¹ for winter wheat, respectively, under the irrigation with TSW. We also obtained the alternative irrigation management practices for the hydrologic years of 75%, 50% and 25%, respectively, in Beijing area under the conditions of irrigation with TSW and the optimal nitrogen application.     

Simulating water content, crop yield and nitrate-N loss under free and controlled tile drainage with subsurface irrigation using the DSSAT model

In southwestern Ontario, rain-fed crop production frequently fails to achieve its yield potential because of growing-season droughts and/or uneven rainfall distribution. The objective of this study was to determine if the Decision Support System for Agrotechnology Transfer (DSSAT) v4.5 model could adequately simulate corn and soybean yields, near-surface soil water contents, and cumulative nitrate-N losses associated with regular free tile drainage (TD) and controlled tile drainage with optional subsurface irrigation (CDS). The simulations were compared to observations collected between 2000 and 2004 from both TD and CDS field experiments on a Perth clay loam soil at the Essex Region Conservation Authority demonstration farm, Holiday Beach, Ontario, Canada. There was good model-data agreement for crop yields, near-surface (0-30 cm) soil water content and cumulative annual tile nitrate-N loss in both the calibration and validation years. For both TD and CDS, the CENTURY soil C/N model in DSSAT simulated water content and cumulative tile nitrate-N loss with normalized root mean square error (n-RMSE) values ranging from 9.9 to 14.8% and 17.8 to 25.2%, respectively. The CERES-Maize and CROPGRO-Soybean crop system models in the DSSAT simulated corn and soybean yields with n-RMSE values ranging from 4.3 to 14.0%. It was concluded that the DSSAT v4.5 model can be a useful tool for simulating near-surface soil water content, cumulative tile nitrate-N losses, and corn and soybean yields associated with CDS and TD water management systems.     

不同灌水方式下春玉米的根系生长分布

为了研究不同灌水方式对春玉米根系分布的影响,在大田条件下对玉米进行垄植沟灌,设计常规沟灌（CI）、交替隔沟灌溉（AI）和固定隔沟灌溉（FI）3种灌水方式.结果表明,（0,40]cm土层中,根长密度以AI较大,FI较小;（60,100]cm土层中,CI下根长密度较小;FI下的植株两侧根长密度差异明显,CI和AI与之相反.（0,100]cm土层中,监测时期内,AI下的玉米总根长和总根干质量都较大.相较FI,AI下的籽粒产量、生物产量和灌溉水利用率分别提高17.37%,18.42%和17.45%.CI表现介于AI与FI之间.抽雄期、植株两侧和（0,40]cm土层根系生长分布受土壤含水率影响较大.可见,局部灌溉对深层根系生长有利,抽雄期植株两侧（0,40]cm土层根系生长分布受灌水方式影响最大;CI与AI下的根系分布相对均匀;与FI和CI相比,AI方式既能促进根系生长,也有利于产量和灌溉水利用率的提高.     

Epistics: A dynamic model to generate nitrogen fertilisation and irrigation schedules in apple orchards, with special attention to qualitative evaluation of the model

Epistics is a model combining a biophysical and a decisional model designed to generate irrigation and N fertilisation schedules in apple orchards. These techniques were chosen since they are key elements in the management of fruit tree cropping systems. The biophysical model representing water and N dynamics in orchards was based on the water and N dynamics of Stics and was completed using a crop water and N requirement estimation method adapted to orchards. It was linked to an agronomic decision rule in a combined model able to generate N fertilisation and irrigation schedules. The Epistics evaluation process dealt with numerical evaluation of state variables (water and N soil content) and qualitative evaluation of model-generated schedules. The numerical evaluation, which concerned the biophysical model of Epistics, was performed on the basis of (i) soil nitrate and water content at the end of winters 2002 and 2003, and on (ii) nitrate and water dynamics during spring and summer 2003. The mean Root Mean Squared Error (RMSE) between observed and simulated values at the end of winter was 3.3% water per horizon and 56 kg N/ha, which is relatively good owing to the high spatial and temporal variability of soil water and nitrate content. The qualitative evaluation of generated schedules was performed during interviews with farmers. Farmers were asked to evaluate the model with reference to their own practices. A sharp difference between farmers and the model concerned the beginning of the irrigation period. This suggested that the model should take into account the constraints imposed by scab and codling moth control practices and irrigation rounds. The difference between model-generated and farmers’ fertilisation practices suggested that the model may take plot vigour into account in the fertilisation decision rule. Such a study is a first step towards the design of models linking sound agronomic decision rules to crop modelling and representing interactions between practices.     

稻秆气化焦油催化裂解脱除过程模型改进与优

对所建立的稻秆气化焦油催化裂解脱除过程LS-SVM模型进行了改进,将原模型的核函数由高斯径向基RBF核函数改为线性lin核函数,并对改进以后的模型进行了验证,在此基础上对稻秆气化焦油催化裂解过程作了优化.结果表明,改进以后的模型具有更好的模拟效果和泛化能力,且当催化裂解温度为949.1356℃,气相停留时间为0.9819s时,焦油催化裂解率达到最大值98.6877%.     

Development and evaluation of a pastoral simulation model that predicts dairy cattle performance based on animal genotype and environmental sensitivity information

A dairy cattle simulation model for pastoral systems that considers how dairy cow genotypes respond to different environments is described. The dairy cow is represented by five modules for maintenance, pregnancy, growth, body energy reserves and lactation with the influence of environmental factors on processes included within each module. Feed intake is predicted based on the requirements for maintenance, growth and pregnancy, and the dairy cow’s potential for yields of milk, fat and protein and body fat change in a given environment. The effects of various temporary environmental factors such as cow body condition score, climate, feed quality and the stage of pregnancy are all considered when predicting yields of milk, fat and protein, energy and dry matter intake. The model was evaluated using information from a prior experimental study with 1990s Holstein-Friesian dairy cattle of North American/European or New Zealand origin managed in a pasture-based system in early to peak lactation. The model was able to predict, to a high degree of accuracy, mean values for yields of milk, fat and protein, and concentrations of fat and protein. However for individual cows, feed intake and live weight change were less reliably predicted. The major source of error was a lack of simulated variation, rather than any systematic bias. The major advance of the model is its ability to predict performance from genetic and environmental sensitivity information for particular breeds, and its ability to predict feed intake and yields of milk, fat and protein concurrently.