Integrated Soil-crop System Management Research Articles

Integrated Soil–Crop System Management Promotes Sustainability of Intensive Vegetable Production in Plastic Shed Systems: A Case Study in the Yangtze River Basin, China

Excessive fertilizer input, low nutrient use efficiency, soil quality, and environmental degradation hinder greenhouse vegetable production. Integrated agronomic strategies of soil, crop, and nutrient management are needed to sharply improve the vegetable yield and simultaneously maintain sustainable production. A three-season field experiment was conducted from 2015 to 2018, aiming to evaluate the effect of integrated soil–crop system management (ISSM) on the agronomy, environment, and economy of greenhouse vegetable systems in the Yangtze River Basin, China. Three treatments were included in the experiment: (1) farmers’ current practice (FP), based on a local farmers’ survey; (2) soil remediation treatment (SR), the application of soil conditioner and compost fertilizer instead of chicken manure; (3) ISSM, a combination of soil conditioner, reducing plant density, and using formula fertilizer as well as increasing the fertilization times. The results indicated that ISSM (47.7 Mg ha−1) improved the pepper yield by 17% relative to farmers’ current practice (FP, 40.7 Mg ha−1). Soil remediation (SR), as a single approach, mainly made a contribution to improving the yield (by 6.9%) and nutrient use efficiency while reducing apparent nitrogen (N) losses. Higher yields were mainly attributed to increasing the fruit number per plant. On average, apparent N losses were reduced by 245 kg N ha−1 per season for ISSM compared to FP. In addition, higher net profits were obtained under SR and ISSM relative to FP. Overall, both SR and ISSM have advantages for the agronomy, environment, and economy in greenhouse vegetable production, but ISSM would be the optimal choice to achieve higher yields with lower environmental impacts.

Long-term maintenance of high yield and soil fertility with integrated soil-crop system management on the Loess Plateau

Ridge–furrow with full film mulching has been widely applied to increase crop yield and water productivity on the Loess Plateau, but it may stimulate carbon (C) mineralization. How to integrate other technological benefits based on this technology for long-term maintenance of high yield and soil fertility is a pressing issue. With the local farmers’ practice (FP) as a control, three integrated soil-crop system management (ISSM) practices integrating fertilizer rates, fertilizer types and planting densities (ISSM-N1, ISSM-N2 and ISSM-MN) were established to improve maize yield and soil quality. Compared with the FP, the maize yield increased by 13.34%, 21.83% and 30.24%, and the soil quality index (SQI) increased by 9.66%, 14.91% and 38.38% for ISSM-N1, ISSM-N2 and ISSM-MN, respectively. However, ISSM-N1 did not significantly increase yield, and ISSM-N2 increased residual soil nitrate and decreased nitrogen (N) partial factor productivity significantly. Compared to the FP, ISSM practices increased soil organic carbon (SOC), labile organic C fractions (LOCFs) and potassium permanganate organic C fractions in the topsoil to varying degrees, but only ISSM-MN reached significant levels for most C fractions. The sensitivity index indicated very easily oxidizable C (24.6%), easily oxidizable C (24.7%), hot-water extractable C (30.8%), labile organic C (24.7%) and particulate organic C (57.3%) were more sensitive than SOC (22.7%). ISSM-MN sequestered significantly higher C than the other treatments. The results of the relative importance analysis and the structural equation model indicated that LOCFs were the direct contributors to yield, while recalcitrant C (CO) was the indirect contributor, revealing the underlying mechanism that CO decomposed to replenish LOCFs and the total N pool with the water soluble C pool as the transit station. Overall, ISSM-MN is the most promising strategy to improve crop yield and soil fertility in the long term on the Loess Plateau.

Altered Organic Matter Chemical Functional Groups and Bacterial Community Composition Promote Crop Yield under Integrated Soil–Crop Management System

Sustainable agricultural production is essential to ensure an adequate food supply, and optimal farm management is critical to improve soil quality and the sustainability of agroecosystems. Integrated soil–crop management based on crop models and nutrient management designs has proven useful in increasing yields. However, studies on its effects on the chemical composition of soil organic carbon (SOC) and microbial community composition, as well as their linkage with crop yield, are lacking. Here, we investigated the changes in SOC content, its chemical functional groups, and bacterial communities, as well as their association with crop yield under different farmland management based on four farmland management field trials over 12 years (i.e., FP: farmer practice; IP: improved farmer practice; HY: high-yield system; and ISSM: integrated soil–crop system management). The crop yield increased by 4.1–9.4% and SOC content increased by 15–87% in ISSM compared to other farmland management systems. The increased proportion of Methoxy C and O-alkyl C functional groups with a low ratio of Alkyl C/O-alkyl C, but high Aliphatic C/Aromatic C in ISSM hints toward slow SOC decomposition and high soil C quality. The relative abundances of r-strategists (e.g., Firmicutes, Myxobacteria, and Bacteroidetes) was highest under the ISSM. Co-occurrence network analysis revealed highly complex bacterial communities under ISSM, with greater positive links with labile SOC functional groups. The soil fertility index was the main factor fueling crop yields, as it increased with the relative abundance of r-strategists and SOC content. Our results indicated that crop yield advantages in ISSM were linked to the high C quality and shifts in bacterial composition toward r-strategists by mediating nutrient cycling and soil fertility, thereby contributing to sustainability in cropping systems.

Cereal production trends, nutrient use efficiency and its management practices in agriculture: A review

Boosting global food production to meet the escalating demand without distressing the environment is a major challenge of our time. In the present review study, a-59 years global cereal production and fertilizer use trends, nutrients use efficiency (NUE) and some of its management approaches in agriculture were evaluated. Accordingly, the world cereal production increased by 3.4-fold (876.9 to 2979 Mt) from 1961 to 2019, whereas the area of production increased moderately by 1.11 folds. The chemical N, P2O5, and K2O fertilizer consumption in cereal crop production were increased by 9.45 folds (from 6.9 to 65.2 Mt), 4-fold (from 6.6 to 26.3 Mt), and 4.34-fold (from 5.2 to 22.6 Mt), respectively. The estimated world cereal N, P, and K use efficiency is 33%, 16%, and 19%, respectively. The unaccounted 65% of N, 84% of P and 81% of K fertilizer was either remained in the soil or lost to the environment through volatilization, leaching, and run-offs leading to higher environmental and economic costs. Therefore, improving NUE is a crucial step to enhance crop yields, tackle environmental pollution, reduce production costs. Several NUE management approaches were identified such as soil management (use of organic inputs, 4R nutrient stewardship, adoption of modified fertilizer, root-zone nutrient management, etc.), plant management (growing nutrient use efficient cultivars, crop rotation, and so on), integrated soil-crop system management (ISSM), and application of precision agriculture. However, no single management approach solely resulted in higher NUE but rather the combination. Hence this could be applied in agricultural production to improve yield and NUE while minimizing environmental degradation.

Diversification of rice growing areas in Eastern India with integrated soil–crop system management for GHGs mitigation and higher productivity

Mono-cropping, burning of crop residues, imbalanced fertilization and limited use of farm manure are resulting in loss of soil organic carbon (SOC). In this study, integrated soil-crop management (ILMsoil), improved management (IMsoil) and conventional management (CMsoil) was studied to enhance the soil carbon sequestration for mitigation of greenhouse gas (GHG) emissions. The life cycle assessment (LCA) approach was used to estimate carbon footprint from successive crops of rice, mustard and jute with or without intercrops or mixed crops. The adoption of ILMsoil helped in reducing the carbon footprint by 78%. The overall economic yield increased by 25% over IMsoil as well. Net CO2-eq emission was 68% less under ILMsoil as compared to other systems. The reduction in net LCA-GHG emission was mainly due to high SOC sequestration by jute crop and leguminous intercrops and mixed crops. Improved crop diversification and agronomic productivity as used in ILMsoil system may decrease the inputs of non-renewable energy and consequently reduce the emission of GHGs from agroecosystems. Improvement of soil health, minimization in nutrient and water losses, and application of the increased amount of organic fertilizers were found helpful in reducing the carbon footprint. ILMsoil method of cultivation in 0.70 million hectare of jute growing area may reduce about 0.40 million tonnes of CO2-eq from atmosphere every year and provide carbon credit of 1.22 million US$to the farmers of eastern India.

Significant soil degradation is associated with intensive vegetable cropping in a subtropical area: a case study in southwestern China

Abstract. Within the context of sustainable development, soil degradation driven by land use change is considered a serious global problem, but the conversion from growing cereals to vegetables is a change that has received limited attention, especially in subtropical regions. Here, we studied the effects of the conversion from paddy rice to an oilseed rape rotation to vegetable production in southwestern China on soil organic carbon (SOC), total nitrogen (TN), the C/N ratio, pH, phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) based on face-to-face farmer surveys and soil analysis. In the vegetable cropping system, fertilizer application often exceeds the crop demand or levels recommended by the local extension service several times over. Thus, the crop use efficiency of N, P, K, Ca, and Mg was only 26 %, 8 %, 56 %, 23 %, and 28 %, respectively. In the vegetable cropping system studied, SOC, C stock, TN, and N stock were decreased significantly due to low organic inputs from crop residues and high tillage frequency. Furthermore, the soil C/N ratio decreased slightly; available P (AP) in the topsoil increased by 1.92 mg kg−1 for every 100 kg ha−1 of P surplus, and the critical levels of AP and CaCl2-soluble P in P leaching were 104 and 0.80 mg P kg−1. Besides, compared to the current paddy–rape rotation system, a clear trend of soil acidification was observed in the vegetable fields. However, increasing the contents of soil Ca and Mg significantly alleviated topsoil acidification, with the effect increasing over time. Given our findings, the potential benefits of conservation agricultural practices, integrated soil–crop system management strategies, and agricultural technology services for recovering the degraded soil and improving the vegetable productivity are discussed here.

Integrated Soil–Crop System Management with Organic Fertilizer Achieves Sustainable High Maize Yield and Nitrogen Use Efficiency in Northeast China Based on an 11-Year Field Study

To increase crop productivity while reducing environmental costs, an integrated soil–crop system management (ISSM) strategy was developed and successfully adopted in China. However, little information is available on the long-term ISSM effects on maize agronomic and environmental performance. Therefore, we evaluated the effects of ISSM with combining inorganic and organic fertilizers on maize productivity, N use efficiency (NUE) and N balance and losses as compared with farmers’ practice (FP) and high-yielding practice (HY), based on an 11-year field experiment in Northeast China. Maize yield in ISSM (11.7–14.3 Mg ha−1) achieved 97.7% of that in HY and was increased by 27% relative to FP. The excellent yield performance in ISSM was mainly attributed to optimum plant population structure and yield components. Annual N surplus in ISSM was only 7 kg ha−1, which was considerably lower than that in FP (52 kg ha−1) and HY (109 kg ha−1). Consequently, ISSM obtained significantly lower N losses and greenhouse gases emissions and higher NUE. In contrast to FP, crop performance in ISSM showing better sustainability and inter-annual stability. In conclusion, ISSM is an effective strategy to achieve long-term sustainable high crop yields and NUE with less environmental costs in the intensive agricultural system.

Integrated systematic approach increase greenhouse tomato yield and reduce environmental losses

High input - high output greenhouse vegetable systems are responsible for nutrient surpluses and environmental losses. Integrated strategies that improve soil, crop and nutrient management are needed to ensure more sustainable production systems. We conducted a two-year field experiment to evaluate the potential of integrated soil-crop system management (ISSM) practices to improve the productivity and environmental outcomes from an intensive greenhouse tomato production system in the Yangtze River Basin, China. Four treatments were tested: i) farmers' practice (FP); ii) soil remediation (SR), where lime nitrogen with compost addition was the only management strategy; iii) a treatment that combined soil remediation with optimized crop planting density (SRCO), which increased planting density for improving crop yield; and iv) integrated soil-crop system management (ISSM), as a systematic integrated approach, which included the combined optimization of soil remediation, crop optimization, and nutrient management. In the integrated soil-crop system management treatment, nutrient management was optimized through adoption of the most appropriate type (formula) of fertilizer for the crop, rate and application timing of synthetic fertilizer, and by substituting poultry manure with compost. Our results indicated that the fruit yield of the integrated soil-crop system management treatment was 104 t ha−1, 13.4%–37.3% higher than that of the other three treatments. The mean reactive nitrogen loss (81.1 kg N ha−1) and the greenhouse gas emissions (6495 kg CO2-eq ha−1) in the farmers' practice treatment were much higher than in the other three treatments (reactive nitrogen loss: 47.9–54.3 kg N ha−1; and greenhouse gas emissions: 4926–5468 kg CO2-eq ha−1, respectively). The mean nitrogen and carbon footprints of the integrated soil-crop system management treatment were significantly lower than those of other treatments, as a result of both the lower fertilizer nitrogen use and the greater yield. This study indicates that integrated soil-crop system management could produce greater yields and increase net profit with reduced nitrogen inputs, whilst reducing the environmental cost associated with conventional farmers’ practice in plastic-greenhouse vegetable production systems.

Cutting carbon footprints of vegetable production with integrated soil - crop system management: A case study of greenhouse pepper production

In China there is an urgent need to improve the sustainability of vegetable production by increasing yields and reducing the environmental losses. However, whilst various single nutrient management measures have proved successful at reducing environmental losses, they have not simultaneously increased yield. Here, we report on a three-year field experiment that used an integrated soil - crop system management (ISSM) approach, to improve crop (pepper) yield and to cut carbon (C) and nitrogen (N) footprints of greenhouse vegetable production in the Yangtze River Basin, China. Treatments included farmers’ practice (FP) for nutrient inputs, soil and crop management; soil remediation (SR), as a single factor approach to optimize soil management, including control of soil borne pathogens and reduced nutrient input by organic resources; and ISSM, as a systematic integrated approach, which includes the combined optimization of factors, including soil remediation, reduced planting density, and improved timing of inorganic fertilizer applications (rate and form). Measurements of pepper yield and N concentrations were used to calculate N offtake, and the C and N footprints were then calculated using life cycle assessment. The three-year continuous field experiment indicated that the mean pepper yield (fresh weight) from the ISSM treatments were 48 t ha−1, 17% and 10% greater than that of the FP and SR treatments (p < 0.05), respectively. The reactive nitrogen (Nr) losses from the FP, SR, and ISSM treatments were 82, 52 and 59 kg N ha−1, respectively. The greenhouse gas emissions of FP, SR, and ISSM treatments were 7061, 5279 and 5728 kg CO2-eq ha−1, respectively. The N and C footprints of the ISSM treatment were significantly lower than the FP treatment by 39% and 30%, respectively, as a result of both a 46% reduction in N inputs (especially an 80% reduction in organic N inputs) and a greater yield. The yield increase contributed to 26% and 37% the reduction of N and C footprints in ISSM treatment, respectively. Meanwhile, there were no significant difference in the N and C footprints between SR and ISSM. This study highlights that the ISSM strategy can produce greater pepper yields with lower environmental costs, and can contribute to sustainable greenhouse vegetable production, and that SR, whilst being a single factor strategy, is a useful first step towards ISSM.

Producing more with less: reducing environmental impacts through an integrated soil-crop system management approach

Balancing crop productivity with resource use efficiency and beneficial environmental consequences is essential for sustainable agricultural development worldwide. Various strategies and approaches have been proposed and debated, but turning the concept into management practices in the field with measurable outcomes over several scales remains a challenge. An innovative approach, Integrated Soil-Crop System Management (ISSM), for producing more grain with greater nutrient use efficiencies and less environmental pollution is presented. The ISSM approach has been used in China, in field experiments as well as in thousands of farmer fields, to substantially increase the yields of maize, rice and wheat while simultaneously increasing nitrogen use efficiency and reducing environmental footprints. The scientific principle, implementation strategy and procedures of ISSM are discussed and examples of its demonstrated successes at local and regional levels across China are given. Perspectives for further development of ISSM and expanding its potential impact are also proposed and discussed.

Soil and Crop Management Strategies to Ensure Higher Crop Productivity within Sustainable Environments

The rising population and reduction in the amount of land and some other resources have created tremendous pressure on current agricultural producers to meet the increasing food demands. To cope with this challenge, certain key inputs, such as fertilizers and other chemicals, are overused, which are worsening the surroundings. This intensive agricultural production without adherence to ecological sustainability has led to declining soil health, land degradation, and severe environmental problems. So, future efforts to feed the growing population should aim for greater agricultural production within sustainable environments. In this regard, innovative steps are needed, as business-as-usual policies lack the potential to cope with these challenges. The concept of agricultural sustainability and various soil and crop management strategies (SCMS) that have been designed to optimize crop yield under sustainable environmental conditions are discussed, including nutrient management, site specific nutrient management (SSNM), integrated nutrient management (INM), integrated soil fertility management (ISFM), integrated soil-crop system management (ISSM), ridge-furrow mulching systems (RFMS), sustainable water management (SWM), conservation agriculture (CA), sustainable land management (SLM), vertical/sky farming, and integrated crop management, and breeding strategies as well as other approaches combined with technological and behavioural changes. The present review suggests that a sustainable production system can be developed by combining the multifaceted efforts under SCMS practices with short- and long-term preventive measures. Reducing chemicals’ usage, such as that of fertilizers and pesticides, plus improvements in the crop input use efficiency could minimize greenhouse gases emissions while protecting the environment. Sustainable agriculture holds promise for humankind and the planet Earth, and it can be successful if all developed and developing nations stand together to seek ‘our common future’ to produce more food while generating less environmental pressure.

Integrated Soil-Crop System Management Increases Phosphorus Concentrations and Bioavailability in a Primosol

In recent years, integrated soil-crop system management (ISSM), i.e., using crop modeling and advanced nutrient management to redesign the cropping system, has been successfully used to improve crop yield and nutrient-use efficiency in China. However, the effects of ISSM on the properties of soils are not yet clear. Based on a seven-year (2009–2016) field plot trial with continuous corn monoculture, this study compared the effects of ISSM with improved practice (IP), high-yield practice (HY), and current farming practice (FP) on phosphorus (P) forms in an Alluvic Primosol of Northeast China by using chemical and spectroscopic (31P NMR) analyses. The concentrations of total P and Olsen P were in the order FP < IP < HY < ISSM; the order for inorganic and organic P fractions obtained by chemical analysis was also the same except for Ca10-P that showed an opposite order. 31P NMR spectroscopy showed that inorganic orthophosphate, pyrophosphate, orthophosphate monoesters, and orthophosphate diesters were all higher in the surface soil in ISSM treatment than in HY, IP, and FP treatments. Our results suggest that ISSM has a positive effect on the availability of P in soil.

Effects of Integrated Soil-Crop System Management on Soil Organic Carbon Characteristics in a Primosol in Northeast China

AbstractA synchronous increase in crop productivity, nutrient use efficiency, and soil carbon (C) sequestration is important from the point of view of food security and environmental protection. In recent years, integrated soil-crop system management (ISSM), which uses crop models and advanced nutrient management to redesign cropping systems, has been successfully demonstrated to achieve both high crop productivity and high nutrient use efficiency in China, but the effects of ISSM on soil organic C (SOC) characteristics remain unknown. In this study, the effects of current farmers' practice (FP), high-yielding practice (HY), which maximizes yields without considering costs, and ISSM on the content and chemical composition of SOC were studied in a 4-year (2009–2013) field plot experiment with maize (Zea mays L.) monoculture in an Alluvic Primosol in Northeast China. The ISSM resulted in higher soil total organic C (TOC), water-soluble organic C, easily-oxidizable organic C, particulate organic C, and humic acid C compared with HY and FP in the region. The SOC contents in aggregate size fractions generally followed a similar pattern to TOC. Compared with FP, HY decreased the mean weight diameter, geometric mean diameter, percentage of > 0.25-mm water-stable aggregates, and the stability ratio of water-stable aggregates, and increased the structure-deterioration rate and index of unstable aggregates. The opposite trend was observed between ISSM and HY. Solid-state 13C nuclear magnetic resonance spectra of bulk soil showed that ISSM had higher O-alkyl C and aliphatic C/aromatic C ratio, but lower aromatic C, carbonyl C, and alkyl C/O-alkyl C and hydrophobic C/hydrophilic C ratios than HY and FP. Our results suggest that ISSM improves the quantity and quality of SOC and has a positive effect on soil aggregation and aggregate stability.

Global warming potential and greenhouse gas intensity in rice agriculture driven by high yields and nitrogen use efficiency

Abstract. Our understanding of how global warming potential (GWP) and greenhouse gas intensity (GHGI) is affected by management practices aimed at food security with respect to rice agriculture remains limited. In the present study, a field experiment was conducted in China to evaluate the effects of integrated soil–crop system management (ISSM) on GWP and GHGI after accounting for carbon dioxide (CO2) equivalent emissions from all sources, including methane (CH4) and nitrous oxide (N2O) emissions, agrochemical inputs and farm operations and sinks (i.e., soil organic carbon sequestration). The ISSM mainly consisted of different nitrogen (N) fertilization rates and split, manure, Zn and Na2SiO3 fertilization and planting density for the improvement of rice yield and agronomic nitrogen use efficiency (NUE). Four ISSM scenarios consisting of different chemical N rates relative to the local farmers' practice (FP) rate were carried out, namely, ISSM-N1 (25 % reduction), ISSM-N2 (10 % reduction), ISSM-N3 (FP rate) and ISSM-N4 (25 % increase). The results showed that compared with the FP, the four ISSM scenarios significantly increased the rice yields by 10, 16, 28 and 41 % and the agronomic NUE by 75, 67, 35 and 40 %, respectively. In addition, compared with the FP, the ISSM-N1 and ISSM-N2 scenarios significantly reduced the GHGI by 14 and 18 %, respectively, despite similar GWPs. The ISSM-N3 and ISSM-N4 scenarios remarkably increased the GWP and GHGI by an average of 69 and 39 %, respectively. In conclusion, the ISSM strategies are promising for both food security and environmental protection, and the ISSM scenario of ISSM-N2 is the optimal strategy to realize high yields and high NUE together with low environmental impacts for this agricultural rice field.

Net global warming potential and greenhouse gas intensity from the double rice system with integrated soil–crop system management: A three-year field study

The impact of integrated soil–crop system management (ISSM) on net global warming potential (GWP) and greenhouse gas intensity (GHGI) is poorly documented though crucial for food security and nitrogen fertilizer use efficiency (NUE). Using local farming practices (FP) and no nitrogen (NN) as the controls, three ISSM practices at different N rates were established in 2009 in a double rice system in Hunan Province, China. Soil organic carbon sequestration rates (SOCSR) were estimated by changes in SOC between 2009 and 2014. Field measurements of methane (CH4) and nitrous oxide (N2O) fluxes, grain yield and NUE of early and late rice were measured from April 2011 through April 2014. The net GWP of the annual CH4 and N2O emissions and SOCSR and the GHGI over the three years in the FP was 15.35 t CO2 eq ha−1 year−1 and 1.00 kg CO2 eq kg−1 grain. The ISSM (N2) treatment increased annual rice yield by 23%, NUE by 76% and SOCSR by 129%, with similar sizes of net GWP and GHGI under the same N input relative to the FP. A second ISSM (N1) treatment in which annual fertilizer N input was decreased by 20% also showed the potential to lower net GWP and GHGI and increase SOCSR and significantly increased annual rice grain yield by 8.6% and NUE by 59%. The third ISSM (N3) in which fertilizer N input was 20% greater than in FP, significantly increased annual rice yield by 26%, NUE by 57% and SOCSR by 98% but notably increased the CH4 and N2O emissions. Our findings show that the ISSM strategies are promising and feasible in sustainable rice agriculture for food security and GHGs mitigation.

Optimised nitrogen fertiliser management achieved higher diversity of arbuscular mycorrhiza fungi and high-yielding maize (Zea mays L.)

The integrated soil–crop system management (ISSM) approach can potentially mitigate the loss of biodiversity in agricultural landscapes, ensuring crop yield with lower nitrogen (N) fertiliser input and minimised environmental pollution. The aim of this study was to test the hypotheses that overuse of N fertiliser could reduce the biodiversity of arbuscular mycorrhizal fungi (AMF) and that ISSM could help to maintain higher AMF biodiversity than the conventionally managed system in maize (Zea mays L.). The AMF community composition under three different treatments (conventionally managed, N-optimised and non-N-fertilised fields) was assessed by using both spore-based morphological taxonomy and DNA-based T-RFLP fingerprinting approaches. Maize roots in intensively managed fields formed functioning mycorrhizal symbioses even when a high rate of N fertiliser was applied. AMF diversity was higher under optimised N input, whereas AMF richness decreased when more N fertiliser was used. The N-optimised farms had AMF communities similar to those in the conventionally managed fields. The ISSM approach is recommended for sustaining crop yields without incurring continuing environmental costs and for maintaining AMF communities in intensively managed agro-ecosystems, especially in rapidly developing countries.

Two approaches for net ecosystem carbon budgets and soil carbon sequestration in a rice–wheat rotation system in China

Few studies have comprehensively evaluated the method of estimating the net ecosystem carbon budget (NECB). We compared two approaches for studying the NECB components on the crop seasonal scale as validated by the soil organic carbon (SOC) changes measured over the 5-year period of 2009–2014. The field trial was initiated with four integrated soil–crop system management (ISSM) practices at different nitrogen application rates relative to the local farmer’s practices (FP) rate, namely, N1 (25 % reduction), N2 (10 % reduction), N3 (FP rate) and N4 (25 % increase) with no nitrogen (NN) and FP as the controls. Compared with the FP, the four ISSM scenarios of N1, N2, N3 and N4 significantly increased rice yields by 9.5, 19, 33 and 41 %, while increasing the agronomic nitrogen use efficiency (NUE) by 71, 75, 99 and 79 %, respectively. The SOC sequestration potentials were estimated to be −0.15 to 0.35 Mg C ha−1 year−1 from the net primary production minus heterotrophic respiration approach and −0.32 to 0.67 Mg C ha−1 year−1 from the gross primary production minus ecosystem respiration approach for the 2010–2011 rice–wheat annual cycle. Similarly, the annual topsoil carbon sequestration rate over 2009–2014 was measured to be −0.22 Mg C ha−1 year−1 for the NN plot and 0.13–0.42 Mg C ha−1 year−1 for the five fertilized treatments. Both NECB approaches provided a sound basis for accurate assessment of the SOC changes. Compared to the SOC sequestration rate from the FP, the proposed N3 and N4 scenarios increased the SOC sequestration rates while also improving rice yield and NUE.

Managing Agricultural Nutrients for Food Security in China: Past, Present, and Future

Over the past 2000 yr, agriculture in China has transformed from a low‐input, low‐output organic‐based system to an intensive production system that relies heavily on inorganic inputs. The modern high‐input, high‐output system has provided the nation with basic food self‐sufficiency, although at escalating environmental costs. Meanwhile, crop production has been nearly stagnant since the mid‐1990s, despite continued increases in production inputs, such as chemical fertilizers. In the future, China must increase agricultural output by 50% to meet its growing food demand. New advances to increase agricultural productivity and improve resource (e.g., N and P) use efficiency will be critical in China for sustainable agriculture and ecosystem services. Here, we discuss an integrated soil‐crop system management (ISSM) paradigm that may help achieve the sustainable intensification goal. This paradigm features (i) improving soil quality, (ii) enhancing the use of various nutrient resources, (iii) closing the yield gap, and (iv) effectively reducing N losses. Recent on‐farm trials based on ISSM principles almost doubled corn yield, while fertilizer N amounts were similar to current farming methods. This ISSM in China is a novel agricultural paradigm that can improve food security and environmental quality worldwide, especially in regions of high input with low‐efficiency systems.

Integrated management systems and N fertilization: effect on soil organic matter in rice-rapeseed rotation

Understanding the effects of long-term crop management on soil organic matter (SOM) is necessary to improve the soil quality and sustainability of agroecosystems. The present 7-year long-term field experiment was conducted to evaluate the effect of integrated management systems and N fertilization on SOM fractions and carbon management index (CMI). Two integrated soil-crop system management (ISSM-1 and ISSM-2, combined with improved cultivation pattern, water management and no-tillage) were compared with a traditional farming system at three nitrogen (N) fertilization rates (0, 150 and 225 kg N ha−1). Management systems had greater effects on SOM and its fractions than did N fertilization. Compared with traditional farming practice, the integrated management systems increased soil organic carbon (SOC) by 13 % and total nitrogen (TN) by 10 % (averaged over N levels) after 7 years. Integrated management systems were more effective in increasing labile SOM fractions and CMI as compared to traditional farming practice. SOC, TN and dissolved organic matter in nitrogen increased with N fertilization rates. Nonetheless, N addition decreased other labile fractions: particulate organic matter, dissolved organic matter in carbon, microbial biomass nitrogen and potassium permanganate-oxidizable carbon. We conclude that integrated management systems increased total SOM, labile fractions and CMI, effectively improved soil quality in rice-rapeseed rotations. Appropriate N fertilization (N150) resulted in higher SOC and TN. Though N application increased dissolved organic matter in nitrogen, it was prone to decrease most of the other labile SOM fractions, especially under higher N rate (N250), implying the decline of SOM quality.

Net global warming potential and greenhouse gas intensity of annual rice–wheat rotations with integrated soil–crop system management

The impact of management practices on the net global warming potential (GWP) and greenhouse gas intensity (GHGI) of rice cropping systems is not well documented. A field experiment was established in 2009 to gain insight into the net ecosystem carbon budget and the net GWP and GHGI on the crop seasonal scale over two cycles of rice–wheat rotations. With the local farmer's practices (FP) as the control, three integrated soil–crop system management (ISSM) practices at different nitrogen (N) application rates were established – ISSM-N1, ISSM-N2 and ISSM-N3 – for improvement of rice yield and agronomic nitrogen use efficiency (NUE). Compared with the FP, the rice yields significantly increased by 8.2%, 18% and 31%, while the agronomic NUE increased by 68%, 74% and 99% for ISSM-N1, ISSM-N2 and ISSM-N3, respectively. Within the three ISSM practices averaged over the two cycles, the soil organic carbon sequestration potentials, CH4 and N2O emissions were estimated to be 0.089–0.67tCha−1yr−1, 166–288kgCH4Cha−1yr−1 and 4.27–5.47kgN2ONha−1yr−1, respectively. Compared to the net GWPs (8.36tCO2eqha−1yr−1) and GHGI (0.58kgCO2eqkg−1 grain) from the FP, the ISSM-N1 and ISSM-N2 reduced both the net GWPs and GHGIs to some extent, indicating that GHG mitigation can be simultaneously achieved with improved food production and NUE. Although it produced similar GHGIs, the ISSM-N3 increased the net GWPs by 16% compared to the FP, indicating that more research is required on ISSMs for mitigating GHGs to further increase the grain yield and NUE in rice agriculture.