On-farm Field Experiments Research Articles

Controlled drought stress affects rosemary essential oil composition with minimal impact on biomass yield

Rosemary (Salvia rosmarinus Spenn.), an indigenous medicinal and aromatic plant within the Mediterranean region, yields essential oils renowned for their antimicrobial, antioxidant, anticancer, and anti-inflammatory properties. When subjected to various stress conditions, rosemary intensifies the production of essential oils as a defensive mechanism, as occurs when it is subjected to drought stress, making it a potentially interesting crop for marginal dryland areas of Sicily and other Mediterranean areas. Managing rosemary cultivation through controlled drought stress close to the balsamic period may increase the concentration and quality of essential oils and optimize the use of limited resources like water. We conducted two on-farm field experiments in Sicily, southern Italy, to assess the effect of controlled drought stress on rosemary biomass, essential oil yield, and composition. The hypothesis was that drought could improve the concentration of essential oils and modify their chemical composition by increasing valuable aromatic components without negatively impacting crop biomass production, increasing interest in cultivating this species. The experiments were co-designed with farmers selecting dedicated field experiments, cultivars, and crop management. Drought stress was applied during autumn and spring in correspondence with medium-high temperatures and rainwater scarcity. The irrigation input was reduced for three weeks during the balsamic period for each trail. Under stressed conditions, morphometric traits were measured. At harvest time, essential oils were extracted using microwave-assisted extraction. Under the same farm conditions, the canopy height was significantly higher in ‘Barbeque’ than ‘Tuscan Blue cv. (67.3 cm vs. 43.8 cm) This indicates a genotype influence on stress response. Essential oil yield increased by 30 % in plants of Tuscan blue cv. subjected to stress conditions in one of two farms. Additionally, drought stress altered the aromatic profile of the essential oil, resulting in differing percentages of key compounds between stressed and unstressed plants. Generally, there was a higher α-pinene percentage in unstressed plants and higher bornyl-acetate and β-caryophyllene concentrations in drought-stressed plants. In the Scicli farm, α-pinene decreased in response to water stress, while camphene and myrcene increased. Our results summarized that controlled drought stress had a minimal impact on rosemary growth, increasing the percentages of some terpenes in its essential oils. No severe decrease was observed in the synthesis of essential oils, suggesting that rosemary is suitable for marginal soils in many Mediterranean countries to protect soils and diversify crops in farms.

Effect of Locally Adapted Conservation Tillage on Runoff, Soil Erosion, and Agronomic Performance in Semiarid Rain-Fed Farming in Ethiopia

An on-farm field experiment on a locally adapted conservation tillage method was undertaken to evaluate its effect on soil erosion, surface runoff, and agronomic parameters. It was conducted on five farmer fields with 3–14% slopes in the Rift Valley and the Eastern escarpment of Ethiopia’s central highlands region for two cropping seasons. The treatments were conventional tillage (CT), repeated ploughing performed with a traditional ox-drawn plough named ‘Maresha’, and minimized contour ploughing (MT) at most twice with a locally adapted sweep-like attachment assembled to Maresha. Surface runoff and soil loss in the MT system were 30 to 60% and 49 to 76% lower than those in the CT system on 3 to 14% slopes, respectively. Despite the wide variation in surface runoff, limited differences in soil water content for the depth from 0 to 20 cm were observed between the treatments. Significant differences (p < 0.05) in grain yields (kg ha−1) of 246 and 323 in the 1st and 2nd growing seasons, respectively, were recorded between the MT and CT treatments. The results of this study demonstrated that the MT system can significantly reduce surface runoff and soil loss while improving crop yields in rainfed smallholder farming systems of Ethiopia.

Effects of Soil Electrical Conductivity and Physical Properties on Seeding Depth Maintenance and Winter Wheat Germination, Development and Productivity

Crop seeding depth is an important parameter in agrotechnologies, but how can seeding depth automatically be maintained in on-farm soil conditions with different textures, granulometric compositions, structural contents and penetration resistances? For this reason, an on-farm field experiment was conducted in the Panevėžys district (Lithuania) during 2020–2022. The field was divided into five zones (EZ1–EZ5) according to soil electrical conductivity. In addition, uniform and variable seeding depths were compared. The results of the investigations showed that soil electrical conductivity was highly correlated with sand (r = −0.867; p ≤ 0.010 > 0.001) and silt (r = 0.871; p ≤ 0.010 > 0.001) contents. The seeding method mainly did not have a significant effect on soil physical properties and winter wheat germination, development and productivity. Higher differences were observed among field zones. The winter wheat seeding depth varied from 27.74 to 33.12 mm between the two most different soil electrical conductivity zones. In zones with variable seeding depths, winter wheat seeds sprouted the most abundantly, and germination reached 99% (in EZ3 and EZ4). In EZ1, EZ2 and EZ4, the yields of grain were the highest and were significantly higher than that in the loamy sand of EZ5. The 1000-grain mass was not affected by any of the tested factors. The results suggest the need for further research in fields with a wider range of soil electrical conductivity. This can increase the variation in seeding depth and reveal interactions among the factors in more detail.

3D characterization of crop water use and the rooting system in field agronomic research

Most field crop phenotyping research has focused on the above-ground parts of crops, ignoring a “hidden half”: the rooting system and its activity. Here we propose and test a new approach to produce 3D characterizations of crop water use and root activity in large field genotype (G) by environment (E) by management (M) experimentation, using electromagnetic induction (EMI) instrument coupled with a quasi-2D inversion algorithm, and crop canopy sensing technologies. A root activity factor (R) was calculated as a function of crop water use, soil water availability, and an indicator of crop demand. We ask i) can this approach provide accurate 3D characterizations of sorghum water use and root activity?, and (ii) does the approach capture complex GxExM dynamics?. This study was conducted based on an on-farm field experiment consisting of the factorial combination of six commercial sorghum genotypes (G), three times of sowing, two levels of irrigation (E), four plant densities (M), and three replications. Two EMI surveys ten days apart were collected using a DUALEM-21S sensor. An artificial neural network (ANN) model was developed to predict 3D soil moisture (θv) using depth-specific true soil electrical conductivity (σ, mS m−1) estimated by the inversion algorithm. Crop water use between surveys was described as the difference of θv. A multispectral index derived from satellite imagery was used as a proxy for crop demand i.e., size of the crop canopy. Principal components analysis, linear mixed models, and recursive partitioning tree techniques and crop-eco-physiological principles were used to untangle complex GxExM interactions. Results indicate that 3D crop water use could be predicted with high accuracy (LCCC = 0.81) and low prediction error (RMSE = 0.03 cm3 cm−3). The calculated water use and the value of R were significantly affected by depth, crop growth stage, irrigation treatment, plant density, and their interactions. At flowering, roots were most active at 0–1.3 m under irrigation, and deeper (0.5–1.5 m) under dryland treatment. The highest water use was for three genotypes (i.e., C, E and F) grown under irrigation and high plant densities (i.e., 9 and 12 pl m-2). The smallest water use was observed under dryland treatment, particularly for two genotypes (i.e., B and C) and high plant densities. For the crops at vegetative stages, the values of water use and R were highest in the top 0.5 m of soil depth. Larger water use was observed under dryland treatment and high plant densities, while the effects of genotypes were small (not significant). We conclude that the approach provides a rapid, accurate and cost-efficient option to phenotype crop root activity i.e., water use, in large field experimentation. We also argue that the improved understanding of the crop water use dynamics can help inform optimum combinations of genotypes and management options i.e., crop designs, across contrasting environments, and help untangle complex GxExM interactions.

Seeding rate, fertiliser and herbicide effects on canopy growth and productivity of direct-seeded rice (DSR) under different management practices

A low seeding rate with seed drill is a good management practice to promote good canopy growth and increase yield of direct seeding rice (DSR) in lowland rice fields. Many studies did not evaluate seeding rates in an integrated way under different management practices in smallholder farmers’ fields. Estimating canopy cover from Canopeo and normalised vegetation difference index (NDVI) may offer a non-destructive, rapid way to assess crop growth and productivity under different field conditions. On-farm field experiments were conducted comparing the yield and canopy growth in response to seed drilled seeding rates of 20, 40, 60 and 80 kg ha −1 and hand-broadcast seeding rates of 180 kg ha −1 (farmers’ practice) grown under different management conditions in Cambodia. In the first experiment, different seeding rates were compared in two villages, Kork Ton Loab (KTL) and Svay Cheat (SVC), in the 2018 growing season. In the second experiment, seeding rates and fertiliser application rates were compared at Kork Ton Loab location in the 2019 cropping season. The third experiment compared seeding rates and pre-emergence herbicide options at Oroung village in the 2018 and 2020 cropping seasons. In experiment 1, sowing at 20 and 40 kg ha −1 consistently decreased mean canopy cover with Canopeo index at Kork Ton Loab and Svay Cheat locations. In experiment 2, sowing at 80 kg ha −1 significantly increased the mean canopy cover compared with 20 and 40 kg ha −1 seeding rates with Canopeo index at 60 and 75 DAS at the Kork Ton Loab location. The low seeding rates of 60, 80 and 180 kg ha −1 increased in canopy cover at 60 DAS with NDVI compared with the lower seeding rates at Kork Ton Loab and Svay Cheat locations. Seeding rates had significant effects on grain yield and gross margin only for experiment 1 and experiment 3 in the 2020 cropping season. For experiment 1, the seed drill rates of 60 and 80 kg ha −1 did not significantly differ in grain yield or gross margin compared with broadcast of 180 kg ha −1 in both locations. Sowing at 20, 40, 60 and 80 kg ha −1 produced similar yield and gross margin at Kork Ton Loab except for the 20 kg ha −1 seeding rate that significantly reduced yield and gross margin at Svay Cheat. For experiment 3, the seed drill of 80 kg ha −1 and 180 kg ha −1 by broadcast (Farmer’s Practice) significantly increased yield up to 3.5 t ha −1 compared with 40 and 60 seeding rates in the 2020 cropping season. Increasing fertiliser rates (high fertiliser; N-100, P-80, and K-50 kg ha −1 ) by two times increased grain yield by 12.8% compared with the low fertiliser rate of N-50, P-40, and K-30 kg ha −1 . Pre-emergence herbicide application significantly increased mean grain yield by 16% and 15% in the 2018 and 2020 cropping seasons, respectively. Therefore, the seed drill of 80 kg ha −1 , high fertiliser rate and pre-emergence herbicide interventions improved uniformity in canopy growth and increased grain yield of DSR. This information can be incorporated into integrated crop and weed management programs for the productivity of direct-seeded rice in the lowland ecosystem. • Low seeding rates (60–80 kg ha -1 ) with seed drill provide similar yield and gross margin as hand-broadcast of 180 kg ha -1 . • The use of vegetation-derived information from reflectance sensors estimates canopy growth in dynamic field conditions. • Sowing at 60 and 80 kg ha -1 with seed drill reduced undesirable agronomic traits compared with hand-broadcast of 180 kg ha -1 .

Assessing the impact of high-input management for reducing soybean yield gaps on high-productivity farms

To increase soybean actual yields (Ya), modern farmers are interested in exploring novel intensification options. We hypothesize that the inclusion of a high-input treatment in high-productivity systems may potentially reduce yield gaps (Yg), representing additional profits for farmers. Our objectives were to: (i) estimate Ya, water-limited yield potential (Ywlim), and Yg; (ii) evaluate a high-input treatment as a management option for reducing Yg; (iii) identify management and environmental factors associated to yield response to inputs and, (iv) determine the economic outcome of this high-input management on high-productivity soybean crops. We carried out 27 on-farm field experiments comparing a conventional management system versus a novel high-input treatment across the Central Pampas of Argentina. The conventional treatment was the most common management prescribed by farmers in the region. The high-input treatment included a set of inputs that were not usually applied and involved soil fertilizers with S and Zn, seeds treated with insecticides, fungicides, and inoculants, stress-reducing product, Ca and B foliar fertilizers and preventive insecticide. The Ywlim was estimated using crop simulation models. Yield gaps were calculated as the difference between Ywlim and Ya. Average Ya and Ywlim were 4571 and 5100 kg ha−1, respectively, with a Yg lower than 30%. High-input treatments promoted a yield response of 131 kg ha−1 across sites (p < 0.001), reducing Yg by 2.6%. Yield response to high-input treatment was positively correlated with Yg and soil pH, but negatively correlated with soil P. No positive economic outcomes were obtained with the high-input treatment. This study showed low benefits of the high-input treatments for reducing Yg in high-yielding soybeans managed by high-productivity farmers. Future yield increases in this type of systems would rely on genetic improvement of soybean yield potential and exploiting genotype x management x environment interactions.

Model for Predicting Rice Yield from Reflectance Index and Weather Variables in Lowland Rice Fields

Smallholder rice farmers need a multi-purpose model to forecast yield and manage limited resources such as fertiliser, irrigation water supply in-season, thus optimising inputs and increasing rice yield. Active sensing tools like Canopeo and GreenSeeker-NDVI have provided the opportunity to monitor crop health and development at different growth stages. In this study, we assessed the effectiveness of in-season estimation of rice yield in lowland fields of northwest Cambodia using weather data and vegetation cover information measured with; (1) the mobile app-Canopeo, and (2) the conventional GreenSeeker hand-held device that measures the normalised difference vegetative index (NDVI). We collected data from a series of on-farm field experiments in the rice-growing regions in 2018 and 2019. Average temperature and cumulative rainfall were calculated at panicle initiation and pre-heading stages when the crop cover index was measured. A generalised additive model (GAM) was generated using log-transformed data for grain yield, with the combined predictors of canopy cover and weather data during panicle initiation and pre-heading stages. The pre-heading stage was the best stage for grain yield prediction with the Canopeo-derived vegetation index and weather data. Overall, the Canopeo index model explained 65% of the variability in rice yield and Canopeo index, average temperature and cumulative rainfall explained 5, 65 and 56% of the yield variability in rice yield, respectively, at the pre-heading stage. The model (Canopeo index and weather data) evaluation for the training set between the observed and the predicted yield indicated an R2 value of 0.53 and root mean square error (RMSE) was 0.116 kg ha−1 at the pre-heading stage. When the model was tested on a validation set, the R2 value was 0.51 (RMSE = 925.533 kg ha−1) between the observed and the predicted yield. The NDVI-weather model explained 62% of the variability in yield, NDVI, average temperature and cumulative rainfall explained 3, 62 and 54%, respectively, of the variability in yield for the training set. The NDVI-weather model evaluation for the training set showed a slightly lower fit with R2 value of 0.51 (RMSE = 0.119 kg ha−1) between the observed and the predicted yield at pre-heading stage. The accuracy performance of the model indicated an R2 value of 0.46 (RMSE = 979.283 kg ha−1) at the same growth stage for validation set. The vegetation-derived information from Canopeo index-weather data increasingly correlated with rice yield than NDVI-weather data. Therefore, the Canopeo index-weather model is a flexible and effective tool for the prediction of rice yield in smallholder fields and can potentially be used to identify and manage fertiliser and water supply to maximise productivity in rice production systems. Data availability from more field experiments are needed to test the model’s accuracy and improve its robustness.

Impacts of eucalyptus biochar application on greenhouse gas emission from an upland rice–sugarcane cropping system on sandy soil

Summary An on-farm field experiment was conducted in northeastern Thailand to assess the effects of different eucalyptus biochar (BC) application rates, in combination with mineral fertilizers, on upland rice and a succeeding crop of sugarcane on sandy soil. Soil mineral N and greenhouse gas emissions were also evaluated. The field experiment consisted of three treatments: no biochar (BC0), 3.1 Mg ha−1 of biochar (BC1), and 6.2 Mg ha−1 of biochar (BC2). All treatments received the same recommended fertilizer rate. Soil mineral N, and emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) were monitored after BC application. The results revealed that the BC2 treatment caused lower soil mineral N content than that of the BC0 treatment during the upland rice period. During the sugarcane period, the BC2 treatment induced a greater soil mineral N content than the BC1 treatment but had no significant difference from the BC0 treatment. The BC2 treatment resulted in significantly lower cumulative CH4 and N2O emissions than the BC0 treatment during the upland rice period. In conclusion, we found that the BC2 treatment alleviated the global warming potential from CH4 and N2O emissions throughout the experiment, causing slight changes in soil N availability in the upland rice–sugarcane cropping system.

Soil phosphorus retention can predict responses of phosphorus uptake and yield of rice plants to P fertilizer application in flooded weathered soils in the central highlands of Madagascar

Efficient phosphorus (P) fertilizer management is highly required for resource-limited farmers to achieve higher yields in typical P-deficient farmlands in sub-Saharan Africa. Although soil P retention has been conventionally used to estimate the possible responses to P fertilizer applied to soils, its applicability has not been clearly confirmed at the field level. In this study, the applicability of P retention to predict the response of rice plants to P application was investigated using pot experiments with soils collected from various locations (N = 62) and on-farm experiments at two nutrient-poor sites (N = 38) in the central highlands of Madagascar. Further, we explored a simple prediction method of P retention for multiple location assessment in local farmers’ fields using an alternative property of soils collected from rice fields in the same region (N = 213). P retention was negatively correlated with the increase in rice P uptake (ΔPuptake, r = − 0.550) in the pot experiment and with the increase in yield (ΔYield, r = − 0.697) in the on-farm field experiment as a response to P application. Path analysis revealed that oxalate-extractable aluminum (Alox) content was the most important factor of P retention across all the soils, indicating that rice plants grown on soils with higher Alox and P retention are less sensitive to P application. Given its high correlation with P retention (r = 0.642) and its simplicity in measurement, we proposed the use of moisture content of air-dried soils (ωair) as a parameter to predict soil P retention. It was further confirmed that ωair had a significant negative correlation with ΔPuptake based on the pot experiment across a wide range of soil statuses (r = − 0.518). However, ωair could not clearly explain ΔYield within a small range of soil properties in the field experiment. Overall, soil P retention can predict the responses of rice plants to P application in the typical P-deficient and low-yielding lowlands in the central highlands of Madagascar, and this simple evaluation technique using air-dried soil moisture content will be helpful for the assessment of multiple rice fields on a broad scale.

Enhancing Sustainable Potato Production—A Case Study in Northern China

Potato is the fourth most important staple crop in China. To meet the increased demand and environmental objectives, potato production should be enhanced by sustainable practices that aim to maximize yield and resource use efficiencies and minimize environmental impacts. Most experiments so far have taken place on experimental stations, while on-farm experimentation is needed to evaluate, demonstrate and scale more sustainable practices. On-farm field experiments were conducted in two years (2017, 2018) in northern China to investigate and demonstrate the effects of different nitrogen (N) fertiliser and irrigation input levels on potato yield, quality, resource use efficiency and environmental impacts. The 2017 experimental results on one farmer’s field showed that under irrigated conditions, adding N fertiliser (from 0 to 267 kg ha−1) did not increase yield due to the high soil N supply, rather it reduced tuber quality. The 2018 experimental results, in which four additional farmers were involved, indicated that, under irrigated conditions, reducing N fertiliser from the current rates (189–252 kg ha−1) to lower levels (109–181 kg ha−1) did not affect yield nor quality; while further reducing N fertiliser inputs (to 9–117 kg ha−1) resulted in a yield reduction (18% on average) in some fields. In both years, irrigation improved tuber yield and quality compared to that under rainfed conditions. The nitrogen use efficiency was improved and N surplus was reduced by applying irrigation and reducing N fertiliser input. Farmers expressed they were willing to reduce N fertiliser input by 10–20%, and indicated that a widespread adaptation of drip irrigation is hindered by the high costs and labor requirements. Site-specific recommendations on optimum N fertiliser and irrigation management must be provided, which should preferably be based on regular quantitative monitoring of soil N supply and soil moisture content.

Growth, productivity, physical and economic optima and yield gaps estimation in wheat (Triticum aestivum L.) through site specific nutrient management approaches under inner-Terai region of Chitwan, Nepal

An on-farm field experiment was accomplished during the winter season of 2018/19 under inner Terai region at Khairahani, Chitwan for evaluating the influence of various site specific nutrient management approaches on growth, yield, optimum fertilizer dose and yield gaps of wheat (Triticum aestivum, L.). The experiment was laid out in Randomized Complete Block Design (RCBD) in three replications with different eight nutrient management practices: T1- farmers fertilization practice (FFP) (52:33:18 kg NPKha-1), T2 - Blanket recommendation (BR) (100:50:25 kg NPK ha-1), T3 - SSNM-NE (110:47:46 kg NPK ha-1),T4 - LCC-N+NE-P&amp;K, T5 - NE-N + farmers -P&amp;K, T6 - LCC- N + farmers–P&amp;K, T7 - Nitrogen Omission Plot (NOPT) + NE- P&amp;K, and T8 - NARC recommendation (120:60:40 kg NPK ha-1). The result findings indicated that the NARC recommendation was comparatively superior over other treatments in terms of plant height, dry matter accumulation, crop growth rate and yield, but the profitability (B:C ratio) was found higher in SSNM-Nutrient Expert recommendation. The physical and economic optimum level of fertilizer for wheat obtained was 135:47.66:43.94 kg NPK ha-1 and 130: 47.86:43.61 kg NPK ha-1, respectively. The yield gaps between farmers practice and SSNM-Nutrient Expert was found to be 110% and 41%, respectively over potential yield of wheat. Thus, it could be suggested that there is great potential to improve the yield of wheat through the NARC recommendation and the SSNM- Nutrient Expert model to raise sustained productivity and income of wheat farmers in inner-Terai region of Nepal.&#x0D;

Converting maize production with low emergy cost and high economic return for sustainable development

Promoting more sustainable agriculture while simultaneously meeting the increased demands for food due to the growing population is a great challenge in the 21st century. Here we addressed this challenge by conducting on-farm field experiments at 40 sites across the broad aro-ecological maize region in China during 2017–2018. According to a modern understanding with emergy and economic aspects, a set of new variety-based low emergy system was developed. Compared with the current traditional farmers’ system, the new system improved the sustainability (emergy sustainability index) by 19% and increased economic return by 47% while similar productivity (maize yield) was achieved. More than 80% of the modeled yield potential was realized. Moreover, the decrease of nonrenewable materials input in the new system contributed to 88% of the sustainability improvement. As food and resource concerns become more severe in many global regions, this new system is likely to supply a typical case and could be adopted widely to realize the United Nations Sustainable Development Goals (SDGs) in agricultural transformation.

Integration of fish culture and poultry rearing in transplanted rice for nutritional security in smallholder farms

Agriculture provides livelihood for 65% of Nepal’s population contributing for 27% of its GDP. Smallholder farms constitute 60% of farming segment. Distress farming, with inadequate minimum support price, subsidies and inadequate revenue generation force 29% of the general population to be malnourished. Farming system designs with integration of animal components would augment animal protein intake of these resource-poor populations, livelihood enhancement and sustainability of production system. On-farm field experiments in 75 participating farmers fields of Nepal with integration of fish culture and poultry rearing in transplanted rice showed appreciable (a significant) increase in nutritional status and livelihoods of participating farmers.

Organic Fertilizer Titonia Plus and Micro Nutrients Improved Rice (Oryza sativa L.) Production in Koto Panjang and Koto Tingga, Padang City, West Sumatera, Indonesia

A series of on-farm fi eld experiments were conducted in two locations in Padang, Koto Panjang and Koto Tingga, West Sumatera, Indonesia in 2015. The purpose of the experiment was to establish the formula of organic fertilizer derived from Tithonia supplied with micro nutrients, Zn and Mn, on rice. The experiments were conducted using completely-randomized block design with six treatments and three replications. The treatments were P = Tithonia Organic Fertilizer Plus (TOFP) + 3.0 kg Mn.ha-1, Q = TOFP + 3.0 kg Mn.ha-1+ 3.0 kg Zn.ha-1, R = TOFP + 4.5 kg Mn.ha-1 + 6 kg Zn.ha-1, S= TOFP + 4.5 kg Mn.ha-1+ 9 kg Zn.ha-1, T = TOFP only, U = 100% chemical fertilizer only. Treatment with micro nutrients as addition to TOFP (TOFP+ 3.0 kg Mn.ha-1 and TOFP+ 3.0 kg Mn.ha-1+3.0 kg Zn.ha-1) increased rice grain yield by 80 g per clump.

Physiological Basis of Genotypic Response to Management in Dryland Wheat.

A great majority of dryland wheat producers are reluctant to intensify management due to the assumption that lack of water availability is the most critical factor limiting yield and thus, the response to management intensification would be limited. We conducted on-farm field experiments across three locations and two growing seasons in Kansas using 21 modern winter wheat genotypes grown under either standard (SM) or intensified management (IM) systems. The goals of this study were to (i) determine whether the SM adopted is adequate to reach achievable yields by farmers in the region and (ii) identify differences in responsiveness to IM among a range of modern genotypes. Across all sites-years and genotypes, the IM increased yield by 0.9 Mg ha-1, outyielding the SM system even in the lowest yielding conditions. As expected, the yield response to IM increased with the achievable yield of the environment and genotype. Across all sources of variation, the yield responsiveness to IM was related to increased biomass rather than harvest index, strongly driven by improvements in grain number (and independent of changes in grain weight), and by improvements in N uptake which resulted from greater biomass and shoot N concentration. The IM system generally also increased grain N concentration and decreased the grain N dilution effect from increased yield. Genotypes varied in their response to IM, with major response patterns resulting from the combination of response magnitude (large vs. small) and consistency (variable vs. consistent). Genotypes with high mean response and high variability in the response to IM across years could offer greater opportunities for producers to maximize yield as those genotypes showed greater yield gain from IM when conditions favored their response. For the background conditions evaluated, intensifying management could improve wheat yield in between c. 0.2 and 1.5 Mg ha-1 depending on genotype.

Nitrogen Surplus Benchmarks for Controlling N Pollution in the Main Cropping Systems of China.

Nitrogen (N) surplus is a useful indicator for improving agricultural N management and controlling N pollution. Few studies have developed benchmark values for cropping systems in China, a country with the largest N fertilizer use in the world. We established N surplus benchmarks for 13 main cropping systems, at optimal N management, using results from >4500 on-farm field experiments and a soil surface balance approach. These cropping systems accounted for about 50% of total N fertilizer consumption in Chinese agriculture in 2009. The results showed that N surplus benchmarks for single cropping systems ranged from 40 to 100 kg N ha-1 yr-1 (average 73 kg N ha-1 yr-1), and for double cropping systems from 110 to 190 kg N ha-1 yr-1 (average 160 kg N ha-1 yr-1), roughly twice that of single cropping systems. These N surplus benchmarks may be further refined, following further decreases in N deposition rates and reactive N losses as a result of strict implementation of "4R-nutrient stewardship" and improvements in fertilization techniques and agronomic managements. Our N surplus benchmarks could serve as realistic targets to improve the N management of current conventional practices, and thereby could lay the foundations for a more sustainable N management in China.

Crop responses to subsoil manuring. II. Comparing surface and subsoil manuring in north-eastern Victoria from 2011 to 2012

An on-farm field-experiment was carried out in north-eastern Victoria in 2011 and 2012 to compare the agronomic effectiveness of surface and subsoil manuring on a Chromosol soil with a compacted clay subsoil. Surface manuring involved the surface application of 20 t poultry litter ha–1, whereas subsoil manuring involved deep-banding of the same quantity of litter in 30–40-cm-deep rip-lines, spaced 80 cm apart. Treatments were applied at the start of the first cropping season. The objective of the study was to determine whether surface manuring might produce the large yield responses reported for subsoil manuring. Both manuring treatments increased yields of wheat (Triticum aestivum L.) by &amp;gt;2.3 t ha–1 compared with the unamended control in 2011, when spring rainfall was close to the average. However, only subsoil manuring increased wheat yields in 2012, producing an extra 4.7 t ha–1 above the control, in a year with a very dry spring. This yield response suggests that subsoil manuring would be more effective than surface manuring in the second year after treatment in years with a dry finish.

Crop responses to subsoil manuring. I. Results in south-western Victoria from 2009 to 2012

Subsoil manuring is a practice that involves placing high rates of organic amendments in bands at the base of rip-lines that extend down into the subsoil to a depth of 30–40cm, in order to ameliorate poorly structured clay subsoils. The objective of this study was to determine whether the increases in crop yield from this practice, which occurred at one site in the high-rainfall zone in Victoria from 2005 to 2007, would occur at other sites and in other seasons in south-western Victoria. On-farm field experiments were therefore carried out at three sites in south-western Victoria between 2009 and 2012 to measure the yield responses to subsoil manuring. The study found that subsoil manuring with poultry litter resulted in consistent and recurring increases in estimated grain yield at these sites, with responses occurring with consecutive crops. Increases in estimated grain yield continued for 4 years, with average increases in hand-harvested yield of 3.5 t ha–1 for wheat, 1.6 t ha–1 for canola and 2.3 t ha–1 for faba beans. The estimated increases in grain yield were frequently associated with the increased extraction of deep subsoil water after anthesis. A treatment involving deep-banded nitrogen (N) and phosphorus (P) fertilisers and additional in-crop N, which matched the N and P in the poultry litter, yielded less than the full rate of subsoil manuring in seven of the eight site-years. This suggests that yield responses from subsoil manuring were not solely due to the release of N and P from the deep-banded poultry litter.

Evaluation of different fertilizer management guidelines for boro rice cultivation in south central coastal region of Bangladesh

Abstract Improving productivity and farm income is the challenge for the grower in rice cultivation. Therefore, a series of on-farm field experiments were conducted to evaluate comparative performance of different nutrient management practices in boro rice production in south central coastal region of Bangladesh. The performance of high yielding rice varieties were tested with four fertilizer management options, viz. (i) use of Rice Crop Manager (RCM), (ii) Soil Test Based (STB) fertilizer application, (iii) BRRI Recommended Fertilizer (BRF) application, and (iv) Farmers' Fertilizer Practice (FFP). Fertilizer management practices and variety interacted significantly to influence yield components like panicle m−2, grains panicle−1 and 1000-grain weight of rice. Similarly, grain yield of rice also significantly varied with the interaction of fertilizer management and rice varieties. Application of BRF produced maximum grain yield of boro rice. However, the grain yield produced with RCM was comparable with that of BRF management. The RCM involved lower fertilizer cost than that of BRF and FFP. Hence, the gross return and profit of rice obtained from RCM was similar with that in BRF. The cost dominant analysis confirmed that RCM was economic and profitable fertilizer management practices in southern Bangladesh.

Intercropping maize (Zea mays L.) with lablab (Lablab purpureus L.) for sustainable fodder production and quality in smallholder rural farming systems in South Africa

ABSTRACTAn on-farm field experiment was conducted in South Africa’s rural Moist Tall Grassveld region which is characterized by overgrazing and a reduced grazing capacity. The grassland is sour veld and only provides palatable material during the 6-month growing season. The experiment was conducted to assess the effect of intercropping maize with lablab on maize fodder, grain yield, and quality, social and economic aspects. The results indicated superiority of intercropping over sole cropping, with intercropping treatments showing consistent superiority across 4 years of the experiment. Maize grain and fodder yields were positively influenced by intercropping with lablab. The maize fodder and total fodder yields were higher in intercropped than in sole maize plots. The maize grain DM yield of the first harvest in maize-only treatment was not significantly higher than in M + L treatment. Intercropping significantly increased crude protein of maize leaves and reduced the leaves’ fiber content. Crude protein contents were lower and fiber contents higher in maize stalks and leaves than in lablab. The field trial demonstrated that diverse plant communities in the form of intercropping provide sustainable production, positive environmental, and social impacts through reduced agrochemicals and are economically viable through cost avoidance and savings. The results of this study suggest that including lablab in traditional maize cropping systems can be beneficial when entanglement of maize is avoided by delayed under sowing of lablab.