Improving China’s food and environmental security with conservation agriculture†

China has achieved impressive increases in agricultural output in recent decades. Yet, past approaches centred on a growing use of fertilizers, pesticides, fuel and water are not likely to achieve the required 30–50% additional increases in food production by mid-century. We show that efficiencies of production are falling and the costs of environmental harm are increasing. Agricultural innovations that improve natural capital are urgently needed. Conservation agriculture (CA) is now practised on >8?Mha in China and is offering promising prospects of both enhanced yields and environmental services. Our meta-analysis of 60 papers with 395 observations in China shows notable benefits from CA. Mean yield increase was 4.5% or 263?kg?ha^?1 for wheat, 8.3% or 424?kg?ha^?1 for maize, and 1.65% or 250?kg?ha^?1 for rice. In 34 datasets from 22 published papers (experimental duration: 2–17 years), 26 datasets (76.5%) show that CA increased yield and soil organic carbon (mean SOC increase of >3?g.kg^?1 in 0–10?cm soil depth) when compared with traditional tillage. Key priorities for the spread of more sustainable forms of agriculture in China are national policy and financial support, better coordination across agencies, and better extension for farmers.     

Long-term effects of crop residues and fertility management on carbon sequestration and agronomic productivity of groundnut–finger millet rotation on an Alfisol in southern India

The data from long-term management and cropping systems experiments are needed to assess changes in soil quality, organic carbon pool, and agronomic sustainability. Thus, a 13-year-old soil fertility management experiment was used to assess the impact of crop residues carbon (C) inputs on SOC stock in a rainfed groundnut (Arachis hypogeae L.)–fingermillet (Eleusine coracana (L.) Gaertn) rotation in semiarid alfisol. The application of farmyard manure (FYM) alone or in a combination with chemical fertilizers contributed to higher amounts of C inputs and subsequently to build up a higher SOC pool. Application of 10?Mg?ha^?1 of FYM and a recommended dose of chemical fertilizer (25:21.8:20.7 and 50:21.8:20.7?kg?N, P, K ha^?1 for groundnut and fingermillet, respectively) increased soil SOC pool by 41.2% to 73.0?Mg?ha^?1 with an increase of 9.3?Mg?ha^?1 over 13 years. Both SOC pool and rates of its sequestration were positively correlated with cumulative C input and sustainable yield index. A minimal input of 1.62?Mg?C?ha^?1?yr^?1 is needed to maintain SOC pool at the antecedent level. Balanced application of NPK fertilizers is needed to reduce and reverse the depletion of SOC pool.     

On-Farm Nutrient Balance Studies in the Dry Zone of Myanmar

On-farm experiments to study soil fertility depletion—one of the biophysical factors limiting crop production—were conducted in six villages of central Myanmar during 1997 to 1999. Systematic socioeconomic surveys and analysis of socioeconomic and crop production factors aided the selection of farmers.

Topsoil mineral nitrogen content at the start of the cropping season was high (10–25 mg N kg^?1). Available phosphorous was around the threshold level for most crops, but exchangeable potassium was low. The predominant continuous cropping system of sole groundnut was on average positive for P (0.24 kg ha^?1 y^?1) and K (7.05 kg ha^?1 y^?1) and negative for N (?32.4 kg ha^?1 y^?1). A negative balance for N in the groundnut/pigeonpea (?58 kg ha^?1 y^?1) and mung bean/pigeonpea (?56 kg ha^?1 y^?1) intercropping systems was noted. The nutrient balances were positive in early sesame—late sesame (29 kg N ha^?1 y^?1, 8 kg P ha^?1 y^?1, 33 kg K ha^?1 y^?1) and early sesame/pigeonpea (8 kg N ha^?1 y^?1, 15 kg P h^?1 y^?1, 44 kg K ha^?1 y^?1) production systems while sole sorghum system resulted in positive balance for N (23.8 kg ha^?1 y^?1) and negative balance for K (?3.8 kg ha^?1 y^?1).     

The positive impacts of irrigation schedules on rice yield and water consumption: synergies in Jilin Province,Northeast China

Food and water security in China are inextricably linked to the development of regional economy, especially for regions with temporary or sustained water shortage such as Jilin Province in northeast China. Water-saving irrigation practices are therefore urgently sought to maintain sustainable growth in grain production. To improve knowledge of the effect of irrigation water level on rice yield and water-use efficiency (WUE), we conducted a field experimental study over two growing seasons in central Jilin. The irrigation experiment included four schedules: (1) traditional irrigation (CK), (2) shallow wet irrigation (T1), (3) intermittent irrigation (T2), and (4) controlled irrigation (T3). Soil test pits were used to estimate evapotranspiration and seepage. The study showed that T3 had the highest WUE (1.64?kg/m³). However, the highest rice yield was found in T1 (9867?kg/ha¹) that achieved the second highest WUE (1.63?kg/m³). Compared with CK, T1 and T3 consumed 7.3% and 36.1% less water, respectively. If adopted at the operational scale, these two schedules could help reduce the pressure of local surface water supply and the production costs significantly. The results gained from this study could also have relevant implication in developing an effective irrigation management for other high-latitude regions.     

Climate change impacts on rain-fed and irrigated rice yield in Malawi

There is extensive scientific evidence on climate impacts and adaptation in rice (Oryza sativa L.), but the majority relates to production in South Asia and China. Only a handful of studies have been conducted in Sub-Saharan Africa and none in Malawi. In this paper, the climate impacts on rain-fed and irrigated rice yield have been assessed by combining the downscaled outputs from an ensemble of general circulation models (GCM) (HADCM3, INCM3 and IPCM4) with data from the LARS-WG weather generator to drive the CERES-Rice crop model. This was calibrated and validated using 10 years (2001–2010) field data from three rice schemes to simulate the baseline (1961–1990) yield (t?ha^?1) and then model future yield changes for selected (B1 and A2) emissions’ scenarios for the 2050s. Although relatively small increases in average yield were projected (+8% and +5% for rain-fed and irrigated rice, respectively), there was large uncertainty (?10% to +20% yield change) when considering different GCMs and emission scenario. Farmer responses to cope with the projected impacts include both autonomous and planned adaptation strategies, such as modifying planting dates to maximize crop growth calendars and available soil moisture, increased use of on-farm water conservation measures and land levelling to improve water efficiency in rice schemes dependent on surface irrigation.     

“Resistance is futile”: estimating the costs of managing herbicide resistance as a first‐order Markov process and the case of U.S. upland cotton producers

A 2012 survey of upland U.S. cotton producers was analyzed to determine the factors contributing to changes in weed management costs (WMCs) after the identification of herbicide‐resistant weeds. An ordered probit regression estimated changes in WMC as a first‐order Markov process. The most important determinants of post‐resistance cost increases were initial WMCs, adoption of labor‐intensive remedial practices, and wick application of herbicides. Cultivation and mechanical/chemical‐intensive practices did not increase WMCs. Post‐resistance changes in WMC ranged between $85 and $138 ha^?1, depending on the practices adopted. WMCs increased by $88 ha^?1 when cost‐neutral practices were adopted. The in‐sample aggregate costs of managing herbicide resistance ranged between $25 and $53 million, depending on the types of adopted practices.     

Yield and income risk-efficiency analysis of alternative systems for rice production in the Guinea Savannah of Northern Ghana

Risk efficiency of rice grain yield and returns to farm operators' household resources generated from an improved short‐duration cover crop fallow system were compared with (traditional) natural bush fallow, and continuous rice‐cropping systems. The improved fallow system involved maintaining Calopogonium mucunoides, seeded into a natural bush fallow for 2 years before planting to rice. With no chemical fertilizer application, which reflects farmers' practice in the area, average grain yield for continuous rice (1,185 kg/ha) and the cropping sequence incorporating a natural bush fallow (1,175 kg/ha) did not differ, but were higher for the improved fallow system (1,304 kg/ha). This suggests that nutrient contribution from the leguminous cover crop made up for critical crop N requirements in the improved fallow. Stochastic dominance of grain yield distributions from the improved fallow system, relative to the other two cropping systems, was more dramatic with no N fertilizer application compared to treatments with 30 kg/ha N. Average returns were highest for the improved fallow system, followed by the natural bush fallow‐cropping system, and then continuous rice, under the no N fertilizer treatment regime. With 30 kg/ha N fertilizer, income risk efficiency was less clear (compared to treatments with no N fertilizer), especially between continuous rice and the improved fallow treatment, because of faster N mineralization effects on continuous rice. In contrast, the improved cover crop fallow system completely dominated the natural bush fallow treatment under both fertilizer regimes. Rice production systems that incorporated the leguminous cover crop fallow were superior to the natural bush fallow system, based on both grain yield and average farm income risk‐efficiency considerations.     

Nitrogen Management for Profitable Farming with Minimal Environmental Impact: The Challenge for Mixed Farms in the Cotswold Hills,England

A detailed nitrogen (N) budget was constructed for a mixed farm in the Cotswold Hills, England, situated on thin, well drained soils prone to leaching. The study covered all stages of the farm's seven-year rotation and included the removal of the dairy herd. All inputs and outputs of N were measured or estimated and a balanced budget achieved, but only by including relatively expensive measurements of soluble organic nitrogen (SON) leached. Leaching was the main loss process. Given the nature of the soil and the influence of the weather, it would be difficult to reduce losses without drastic reductions in fertiliser inputs or stocking rates. Nitrogen use efficiency averaged 46%. The mean N surplus declined from 141 kg N ha^?1 to 117 kg N ha^?1 with the removal of the dairy herd. However, the farm to which the herd moved had an N surplus of 392 kg N ha^?1. Simple farm gate N budgets were constructed for neighbouring Cotswold farms to encourage farmers to consider ways to improve N use. Implications for policy to reduce losses of N while maintaining farm profitability are discussed.     

Assessment and improvement of the efficiency of nitrogen use on commercial dairy farms

Nine dairy farmers participated in a project which ran over a four year period from 1997 to 2001, with the aim of improving nitrogen use efficiency (NE) and reducing nitrogen surpluses. Results from systems research and the disadvantages of large nitrogen losses and low NE to the economics of the farm business and the environment were outlined and possible mitigation strategies were discussed with the farmers during visits by a dairy consultant. Initial nitrogen use efficiency (nitrogen output/nitrogen input) ranged from 10% to 23% and nitrogen surplus from 259 to 785 kg N ha¹. During the project nitrogen efficiency improved by an average of 5.4% and nitrogen surpluses reduced by an average of 186 kg N ha¹. The largest changes in nitrogen output per hectare were due to changes in stocking rate rather than changes in milk yield per cow or milk protein content. Nitrogen input was dominated by nitrogen fertilizer input, which for farms applying more than 150 kg N ha¹accounted for between 41% and 85% of total nitrogen input. Reduction in mineral nitrogen fertilizer use was the main way that farmers improved nitrogen efficiency and reduced nitrogen surpluses.     

Remediation of Abandoned Saline Soils Using Glycyrrhiza glabra: A Study from the Hungry Steppes of Central Asia

Large expansion of the irrigated area in the Aral Sea Basin has exacted a substantial toll on land and water resources in the region. Elevated water tables associated with poor irrigation management and inappropriate drainage infrastructure have resulted in significant secondary salinisation of crop lands resulting in declining cotton and wheat yields and eventual abandonment of lands. Costs associated with the installation of appropriate drainage infrastructure in order to reclaim these areas are prohibitive and hence alternative approaches are required that can be adopted by resource poor farmers. In the current study the potential use of Glycyrrhiza glabra (common name liquorice) to reclaim abandoned saline areas was assessed over a four year period before being returned to a cotton/wheat crop rotation. Two adjacent abandoned fields of 10 and 13 ha respectively were selected for the study on which two treatments were imposed, namely, a control that was maintained as a bare fallow between 1999 and 2003 and a treated plot where liquorice was established over this period. High quality livestock forage with a protein content of 12% was cut from the liquorice plot with dry matter yields ranging from 3.66 (±0.06) to 5.11 (±0.17) t ha^?1. In addition, root dry matter yields of 5.63 (±1.19) to 8.55 (±0.82) t ha^?1 were recorded, this plant component being used in the preparation of herbal medicines and soft drinks. At the end of four years both plots were returned to a wheat and cotton crop rotation. Yields of wheat on the control and treated plots were 0.87 (±0.05) and 2.42 (±0.02) t ha^?1 respectively. Similarly substantial increases in cotton were observed with the control and treated plots yielding 0.31 (±0.01) and 1.89 (±0.18) t ha^?1. These levels of production on the treated plot exceed the district average for wheat and cotton of 1.75 and 1.5 t ha^?1 respectively, clearly showing the positive benefit associated with the growing of liquorice. Water table levels after four years were maintained below the critical level of 2.5 m in the treated plots whilst rising to within 1.99 m from the surface in the control. Salt content of the soil in the treated plot declined over the study while those in the control increased. This preliminary study has clearly demonstrated the ameliorating affect of liquorice in bringing abandoned salt affected soils back into production that is low cost and could be adopted by resource poor farmers.     

The right place to grow rice for the Japanese market: comparative analysis of greenhouse gas emissions of rice cultivation in Japan and the United States

One consequence of increasing agricultural trade is a shift of geographic location of agricultural activity to more economically productive countries. Whether or not the economic efficiency translates to environmental efficiency for agricultural goods is an open question. To examine environmental implications of shifting agricultural location, we analysed the life-cycle greenhouse gas (GHG) emissions of rice production in Japan and the US for the Japanese market in a comparative manner. This paper presents the life-cycle assessment of brown japonica rice. Our computation of GHG emissions of rice production in Japan and the US were 3.54 and 2.99?kgCO₂-eq kg-rice^?1, respectively. With respect to harvested area, the emissions were 18.4 in Japan and 27.8?tCO₂-eq ha^?1 in the US. For Japan to be environmentally competitive with the US production, fundamental restructuration of field size is necessary to increase yield. In conclusion, economic efficiency does not translate to environmental efficiency with the case of rice production. Importing rice is both economically and environmentally viable option for the Japanese market.     

水足迹视角下京津冀县域粮食作物水土资源匹配格局

[目的]农业水土资源是粮食生产的决定因素,探明京津冀粮食生产中水土资源匹配格局特征对区域经济发展有深远的影响。[方法]文章从水足迹的视角出发,分析了1980—2018年京津冀县域5种主要粮食作物（小麦、玉米、稻谷、大豆、薯类）的产量、播种面积、水足迹、耕地面积的时空变化,运用水土匹配系数法及ArcGIS深入研究了1983年、1998年、2003年和2016年水土资源匹配格局,并进一步剖析区域农业水土匹配对农业生产的影响。[结果]（1）当前京津冀水土匹配系数区间为[0.02,1.25],超出区间范围[0.281, 0.431];粮食生产格局与水土匹配系数空间格局均为“冀中南高、北部低”。（2）研究时段内,京津冀粮食总产量提高1.14倍,播种总面积降低19.28%,粮食单产量显著提高;灌溉提高粮食单产量,水土匹配系数与粮食单产量呈正相关。（3） 1980—2019年京津冀5种作物蓝水足迹均值（136.64亿m3）是绿水足迹均值（99.60亿m3）的1.37倍,各作物水足迹变化不同,间接反映地区农业种植结构的改变。（4）京津冀水足迹总量提高2.45倍,耕地总量下降20.59%,水土匹配系数变...     

Assessing the efficiency of switchgrass different cultural practices for pellet production

Switchgrass is a perennial crop producing high amounts of biomass for good quality pellet production. The objective of this study is to examine the efficiency of different cultural practices of switchgrass for pellet production under field conditions for four different N-fertilization (0, 80, 160 and 240 kg ha⁻¹) and two different irrigation levels (0 and 250 mm), in two soils in central Greece with rather different moisture status over the period 2009–2012. Moreover, comparison between three harvest methods (two different types of bales and silage) was made. The results derived from this study revealed that the bale at 22 kg is the harvesting practice with the highest costs while there was reduction of efficiency scores when nitrogen levels increased. At both environments the efficiency scores followed the same trend, confirming that low levels of nitrogen fertilization enhance the economic competitiveness of switchgrass production. Palamas site is the area where switchgrass for pellet production had positive income ranging from 400 to 1600 € ha⁻¹, while Velestino site had always negative. Therefore, places like Velestino with non-aquic soil should be avoided for switchgrass. These data suggest that growing switchgrass for solid biofuel production as energy crop is a worthwhile decision only in areas with a moderately shallow groundwater table (aquic soil) or maybe in high precipitation regions.     

Modelling stochastic crop response to fertilisation when carry-over matters

Soils in a large part of Niger's agricultural area are sandy and very low in nitrogen (N), phosphorus (P) and organic matter. This low soil fertility combined with low and erratic rainfall constitutes a severe constraint on food cropping in the area. Although agronomists have advised chemical fertilization as a means of improving soil fertility, little fertilizer has been used in this area of the world. The economic management of soil fertility in the agricultural area of Niger is analyzed using a dynamic model of farmer decision-making under uncertainty. The model is based on agronomic principles of plant growth and accounts for the carry over of P, an immobile nutrient. At current input prices, a soil P content of at least 14 ppm is found to be desirable. This target is above the natural soil fertility level of about 3 ppm. It can be maintained with a moderate annual application (12 kg P₂O₅ ha^?1) of simple superphosphate. Results also suggests that returns to N fertilization are too low and variable to warrant the use of this input.     

Gliricidia sepium Carbon Inputs and Soil Carbon Pools in a Costa Rican Alley Cropping System

Alternative land management practices, including agroforestry, help to maintain levels of soil organic matter (SOM) and can facilitate soil carbon (C) sequestration for mitigating atmospheric CO₂ emissions. This study quantified C inputs and determined the changes of the soil C pool in a 19-year-old Gliricidia sepium alley cropping system, studied at two fertiliser levels (tree prunings only [? N], and tree prunings plus chicken manure [+ N]), and was compared to a sole crop system. Carbon input from tree prunings ranged from 455 to 457 g C m^{? 2} y^{? 1}, whereas C inputs from crop residues were similar between alley- and sole crops ranging from 121 to 159 g C m^{? 2}y^{? 1}. The soil organic C (SOC) pool in the alley crop was 16–23% higher than the sole crop. In the 19th year of alley farming, SOC was significantly higher (p < 0.05) in the alley crop (3.2%) compared to the sole crop (2.4%), and was also greater compared to that at the time of establishment of the agroforestry system (2.8%). Gross SOC turnover to a 20-cm depth ranged from 12 to 14 years in the + N and ?N alley crops compared to 49 and 50 years in the + N and ?N treatments for the sole crops. Residue stabilisation efficiency in the alley crops was 39% and 55% in + N and ?N treatments respectively.     

Assessing the potential of SRI management principles and the FFS approach in Northeast Thailand for sustainable rice intensification in the context of climate change

The paper describes the facilitated learning process of farmers, its results and implications in addressing the low productivity of Jasmine rice in northeast Thailand using the SRI-FFS approach in a collaborative action research. Other involved included rice traders, millers, researchers, government and non-governmental organizations. Working through an inclusive process of dialogue, observation, diagnosis, experimentation and exposure to different types of innovative agronomic crop management (IACM) practices resulting from the SRI–FFS approach, participants made a thorough analysis of the current management practices and evaluated various IACM practices for their productivity and profitability. The results confirmed the potential of IACM in enhancing crop and water productivity along with soil fertility with relatively low input-use (seed, water and fertilizers) and higher net farm-income compared to existing crop management practices. However, factors such as (i) the age of the farmers and (ii) off-farm employment opportunity are key drivers that affect the crop management decision-making process. Therefore, exploration of value-added production alternatives and favourable policies is required to sustain IACM that can benefit farmers, consumers and the environment. The participation of policy-makers at the action research continuum is essential for effective follow up, scaling up and sustainability of such environmentally sound practices.     

How environmentally (un)sustainable is organic pig production? The Dutch case

Sustainable agriculture is considered as an appropriate alternative to what some would see as the more environmentally harmful conventional agriculture. Among the existing options within sustainable agriculture, organic farming is probably the most widely adopted. Certification of organic products aims to guarantee that organic agriculture rules are satisfied. However, certification does not always relate to sustainable practices. The present work uses database analysis to obtain a general picture of organic pig production in The Netherlands in terms of environmental sustainability. To do so the nitrogen pollution potential and other parameters of the system are evaluated. Farms were divided into four production types: grazing, mixed-vegetable, mixed-husbandry and swine (i.e. pigs). The results presented here reveal that 72% of the farms do not adjust the number of animals to the farm size. Consequently, the production of nitrogen often surpasses the limit stated by the EU (170 kg N ha^?1 y^?1). In general, swinetype farms have smaller farm sizes and are among the most polluting ones. These farms cannot be considered as a land-related production, one of the premises for organic husbandry according to the EU regulation. This illustrates that the fulfilment of the law does not necessarily entail the implementation of organic principles. To address this dilemma, share-land agreements are proposed as an alternative to allow specialized farms to diversify production and support biological cycles within the agroecosystem that emerges from between-farm collaborations.     

Understanding the influence of farmer motivations on changes to soil erosion risk on sites of former serious erosion in the South Downs National Park,UK

Serious soil erosion occurred in the South Downs National Park, southern England in the years 1982–2006 and details of around 400 sites are contained in a database. In 2010 we revisited 85 of the most serious sites where erosion of >10 m³ ha⁻¹ y⁻¹ had been recorded in order to assess land use change and any conservation measures undertaken. At 79% of the sites land use change had resulted in a reduction in the risk of erosion, most notably at 28 sites with a shift to permanent grass from winter cereals. At only 21% of sites was the risk of erosion unchanged. Twenty two farmers responsible for 66 of the sites were interviewed. Land management practices had changed on all of the fields of interest to this study since the time of the serious erosion events, to those which have the potential to lower soil erosion risk. Sixteen interviewees claimed that erosion was a motivating reason for changing their practices, due to either experiencing on or on- and off-farm impacts firsthand (12), having knowledge or suspicion of serious erosion having occurred on their land prior to their management (three), or having no knowledge of any serious erosion on their land but just wanting to reduce overall erosion risk (one). Amongst the main changes reported are changes of land use from winter cereals to grass or to overwinter stubble which have undoubtedly reduced the risk of erosion. However, some changed practices claimed by farmers, such as along-the-contour-working, earlier sowing and the use of rollers may be of little value. Furthermore, deeper analysis of farmers’ motivations regarding changes in land management practices suggests a complex picture in which a range of socio-economic influences come into play over time including financial incentives offered by agri-environmental schemes which were found to be an important driver of change. Future changes in farming economics may therefore undermine the reduction in erosion risk in the longer term.     

An economic approach to soil fertility management for wheat production in north-eastern Australia

Soil fertility decline and soil management for crop production are important economic issues for grain growers in north-eastern Australia. In that region, there is evidence of soil fertility decline which is attributed to past crop management practices. The questions addressed in this article are first, whether components of soil fertility can be improved by better management and second, by how much soil fertility would change. Soil fertility for crop production is considered in terms of soil organic carbon and nitrogen. A stochastic dynamic economic analysis of soil fertility management for wheat production is presented. A sequential analysis of first deriving the optimal nitrogen stock and application rates is followed by an assessment of tillage, stubble, and fertilizer strategies to obtain an optimal level of soil organic carbon. The recommended management practices are consistent with emerging management trends in the region. The derivation of optimal levels of soil fertility for agricultural purposes has other policy implications, which we discuss.     

Reduced tillage and nitrogen effects on soil water dynamics and maize (Zea mays L.) yield under semi-arid conditions

Soil water and nutrients are critical drivers of crop production for smallholders of southern Africa. A three-year study was conducted to assess the effect of integrating single and double ploughing, ripping and planting basins with nitrogen fertilizer (0, 10 and 20?kg?N?ha^–1) on soil water dynamics and maize (Zea mays L.) yields. The experimental design was factorial with four tillage methods and three nitrogen levels as treatment factors. The study was conducted under semi-arid conditions of Zimbabwe. Tillage methods had similar soil water patterns in the profile and no tillage?×?N interaction effects were observed on soil water dynamics. Soil water penetrated deeper into the profile under ripper and basin methods than conventionally ploughed treatments. Nitrogen increased maize yields (14–96%) and rainwater-use efficiency (20–92%) regardless of tillage methods and growing season quality. However, more studies are required to explore complementary techniques that can improve rainwater capture and prolong soil water storage, and improve soil fertility.