Meta-analysis of green manure effects on soil properties and crop yield in northern China
Introduction
The food production industry is under increasing pressure with the rapid growth of the world’s population. How to produce more food on our limited arable land is one of the greatest challenges that agriculture will face in the future (Ibarrola-Rivas et al., 2017; Tiwari et al., 2018). Soil is the basis of agricultural production. The intensive and improper use of land that often results from the pressure of increased food demand leads to the degradation of farmland soil. For example, long-term monocropping causes an imbalance of soil nutrients and the accumulation of harmful elements (Ernst et al., 2018; Qin et al., 2017;Trasar-Cepeda et al., 2008). The excessive use of chemical fertilizers and pesticides in agricultural production has also had a severe negative impact on soil quality (Chhipa, 2017; Ding et al., 2017;Ren et al., 2019). Therefore, how to coordinate food production and ensure the sustainable use of farmland is one of the most urgent issues agriculture is facing today, and sustainable agricultural management techniques are especially needed.
The application of green manure (green manure) is an old agricultural management practice that has re-attracted people’s attention in recent years because of its environmentally friendly properties. A large number of studies have proved the positive effects of green manure application on improving agricultural production in different areas (Couedel et al., 2018;Valkama et al., 2015; Yang et al., 2018). The beneficial effects can be summarized as follows: 1) preventing soil erosion and decreasing the runoff from farmland in the fallow period (Almagro et al., 2016; Sharratt et al., 2018; Singh et al., 2017); 2) reducing soil bulk density and increasing the content of soil organic matter, soil nitrogen, soil phosphorus, soil potassium and other nutrients, and thus reducing the use of chemical fertilizers (Chaudhary et al., 2017; Damon et al., 2014; Li et al., 2015a, 2015b; Thorup‐Kristensen et al., 2003); 3) improving soil biodiversity and enzyme activity, and accelerating soil nutrient transformation (Gao et al., 2016; Kataoka et al., 2017); 4) enabling control of weeds, pests and diseases, which in turn cuts down the use of pesticides (Alvarez-Iglesias et al., 2018; Masilionyte et al., 2017; Puig et al., 2019); 5) increasing crop yields and farmers' profits (Astier et al., 2006; Cordoa et al., 2018; Toom et al., 2019).
In China, the use of green manure in agriculture has a long history but has diminished significantly since the 1980s with the increased use of chemical fertilizers in agricultural production (Cao and Huang, 2009). In recent years, in response to the rapid degradation of farmland soil and the high cost of chemical fertilizers, the use of green manure has been re-evaluated in contemporary agricultural production, and a large number of studies on the application of green manure have been performed (e.g. Xie et al., 2019; Yao et al., 2019; Zhang et al., 2016a, 2016b, 2016c). In southern China, positive effects of green manure on soil improvement and crop yields have been confirmed through a large number of field experiments, which provides useful guidance for practical agricultural production in this area (Gao et al., 2016; Ding et al., 2018; Xie et al., 2017).
As China’s main grain-producing region, the northern region plays an important role in China’s food security (Kuang et al., 2015; Sun et al., 2010). Although many studies on the application of green manure have been conducted in this area, these studies have reached contradictory conclusions (He et al., 2016; Xue et al., 2017; Yang et al., 2014; Zhang et al., 2016a). Compared with southern China, northern China’s climate, crop species and planting systems are more complex, especially due to the region’s limited precipitation, which leads to competition between crops and green manure for the available water resources. On the other hand, most of these isolated case studies have assessed the effect of green manure in terms of a single aspect. Therefore, no single study can provide adequate scientific guidance for the large-scale application of green manure in northern China. In view of this, the agricultural industry needs an integrated analysis of the existing independent research data and a comprehensive evaluation of the effects of green manure on crop production in this region.
Meta-analysis is a comprehensive method of analyzing a series of independent studies. The effect size of meta-analysis enables researchers to quantitatively analyze the effects of treatments applied in different studies (Gurevitch and Hedges, 1999). Due to its rigorous analytical process and quantitative results, meta-analysis has been widely used in agricultural research. As China’s main grain-producing region, northern China has unique planting systems as well as distinctive climatic characteristics; accordingly, any conclusions drawn from integration analyses of other regions may not be applicable to this area. Thus it is necessary to conduct a comprehensive analysis specific to this area. In the current study, we performed a meta-analysis on the effects of green manure on soil physical and chemical properties, soil moisture and subsequent crop yields in northern China. Our report presents comprehensive scientific recommendations for the application of green manure in the planting systems of this region.
Section snippets
Study area
Northern China is located between 73–136 °E longitude and 31–54 °N latitude, with a total area of approximately 5.1 × 10^6 km2 (Zhen et al., 2010). It includes the following provinces: Shaanxi, Gansu, Qinghai, Ningxia, Xinjiang, Beijing, Tianjin, Hebei, Shanxi, Inner Mongolia, Heilongjiang, Jilin, Liaoning and Shandong (Fig. 1). Dominated by a continental monsoon climate, the annual mean temperatures of this region range from −5 to 15 °C, and mean annual precipitation gradually decreases from
Soil bulk density and pH
Compared with the fallow control, green manure treatment decreased soil bulk density significantly, by 5.6 % in the 0–20 cm soil layer and by 4.0 % in the > 20 cm layer. Meanwhile, soil pH showed no significant changes as a result of the introduction of green manure in either the 0–20 cm or the > 20 cm soil layer. (Fig. 2).
Soil biological characteristics
Application of green manure had a significant positive effect on microbial biomass carbon levels and soil enzyme activities. As shown in Fig. 3, soil microbial biomass carbon
Discussion
In practical agricultural production in northern China, farmland is commonly left bare from the harvest of the previous crop to the sowing of the next crop, which provides the spatial and temporal conditions for the application of green manure. Our study found that the application of green manure in this region significantly improved soil fertility and soil enzyme activities (Fig. 3, Fig. 4, Fig. 5, Table 1). These improvements in turn had variable effects on crop yield depending on crop and
Conclusions
In northern China, green manure application during the fallow period can significantly improve soil quality in both the 0–20 cm and the > 20 cm soil layer. Green manure can reduce soil bulk density, enhance soil biological activity, and significantly increase the contents of N, P and K. For the consumption of soil water during its growth period, green manure can lead to the decrease of 0–2 m soil water content. The effect of green manure application on subsequent crops yield varies according to
Declaration of Competing Interest
The authors report no declarations of interest.
Acknowledgements
We appreciate all of the researchers whose data were used in this meta-analysis. This work was supported by the National Key Research and Development Program of China (2018YFD1001003), the National Key Technology R&D Program (2015BAD22B01), and the 111 project of the Chinese Education Ministry (B12007).
References (103)
- et al.
Cover crop effects on soils and subsequent crops in the pampas: a meta-analysis
Soil Tillage Res.
(2017) - et al.
Short-term green manure and tillage management effects on maize yield and soil quality in an Andisol
Soil Tillage Res.
(2006) - et al.
Review of yield gap explaining factors and opportunities for alternative data collection approaches
Eur. J. Agron.
(2017) - et al.
Long-term effects of NPK fertilizers and organic manures on carbon stabilization and management index under rice-wheat cropping system
Soil Tillage Res.
(2017) - et al.
Cover crop crucifer-legume mixtures provide effective nitrate catch crop and nitrogen green manure ecosystem services
Agric. Ecosyst. Environ.
(2018) - et al.
Crop residue contributions to phosphorus pools in agricultural soils: a review
Soil Biol. Biochem.
(2014) - et al.
Manipulating cover crop growth by adjusting sowing time and cereal inter row spacing to enhance residual nitrogen effects
Field Crops Res.
(2019) - et al.
Improving agricultural water use efficiency in arid and semiarid areas of China
Agric. Manage. Water Qual.
(2006) - et al.
Potential benefits of biochar in agricultural soils: a review
Pedosphere
(2017) - et al.
Improving yield and nitrogen use efficiency through alternative fertilization options for rice in China: a meta-analysis
Field Crops Res.
(2018)
Shifting crop-pasture rotations to no-till annual cropping reduces soil quality and wheat yield
Field Crops Res.
Benefits of growing potatoes under cover crops in a Mediterranean climate
Agric. Ecosyst. Environ.
Definitions and determination of crop yield, yield gaps, and of rates of change
Field Crops Res.
Is the available cropland and water enough for food demand? A global perspective of the Land-Water-Food nexus
Adv. Water Resour.
Impact of co-inoculation with plant-growth-promoting rhizobacteria and rhizobium on the biochemical responses of alfalfa-soil system in copper contaminated soil
Ecotoxicol. Environ. Saf.
Hairy vetch (Vicia villosa), as a green manure, increases fungal biomass, fungal community composition, and phosphatase activity in soil
Appl. Soil Ecol.
Evaluation of water and nitrogen use efficiencies in a double cropping system under different integrated management practices based on a model approach
Agric. Water Manage.
Effects of reduced nitrogen input on productivity and N2O emissions in a sugarcane/soybean intercropping system
Eur. J. Agron.
Effect of cover crops in smothering weeds and volunteer plants in alternative farming systems
Crop Prot.
On the suitability of Eucalyptus globulus green manure for field weed control
Crop Prot.
Soil water dynamics under various agricultural land covers on a subsurface drained field in northcentral Iowa
USA. Agric. Water Manage.
Chromium speciation, bioavailability, uptake, toxicity and detoxification in soil-plant system: A review
Chemosphere
Effect of seven years of nutrient supplementation through organic and inorganic sources on productivity, soil and water conservation, and soil fertility changes of maize-wheat rotation in north-western Indian Himalayas
Agric. Ecosyst. Environ.
Effect of precipitation change on water balance and WUE of the winter wheat-summer maize rotation in the North China Plain
Agric. Manage. Water Qual.
Catch crops and green manures as biological tools in nitrogen management in temperate zone
Adv. Agron.
Biochemical properties of soils under crop rotation
Appl. Soil Ecol.
Meta-analysis of the effects of undersown catch crops on nitrogen leaching loss and grain yields in the Nordic countries
Agric. Ecosyst. Environ.
Simulation of bromide and nitrate leaching under heavy rainfall and high-intensity irrigation rates in North China Plain
Agric. Water Manage.
Effects of planting soybean in summer fallow on wheat grain yield, total N and Zn in grain and available N and Zn in soil on the Loess Plateau of China
Eur. J. Agron.
Green manuring effect on changes of soil nitrogen fractions, maize growth, and nutrient uptake
Agronomy Basel
Screen for sustainable cropping systems in the rain-fed area on the Loess Plateau of China
Soil Tillage Res.
Dynamics and sequestration potential of soil organic carbon and total nitrogen stocks of leguminous green manure-based cropping systems on the Loess Plateau of China
Soil Tillage Res.
Estimation of runoff mitigation by morphologically different cover crop root systems
J. Hydrol.
Effects of mulching and catch cropping on soil temperature, soil moisture and wheat yield on the Loess Plateau of China
Soil Tillage Res.
Status of mineral nitrogen fertilization and net mitigation potential of the state fertilization recommendation in Chinese cropland
Agric. Syst.
Resampling tests for meta-analysis of ecological data
Ecology
Sustainable land management practices as providers of several ecosystem services under rainfed Mediterranean agroecosystems
Mitig. Adapt. Strateg. Glob. Chang.
The kill date as a management tool for cover cropping success
PLoS One
Faba bean as green manure for field weed control in maize
Weed Res.
Effect of long-term organic and mineral fertilizer on physical properties in root zone of a clayey Ultisol
Arch. Agron. Soil Sci.
Summer cover crops fix nitrogen, increase crop yield, and improve soil–crop relationships
Agron. J.
Tillage of cover crops affects soil water, nitrogen, and wheat yield components
Agron. J.
Ideas on restoration and development of green manures in China
Soil Fert. Sci. China
Nanofertilizers and nanopesticides for agriculture
Environ. Chem. Lett.
Revisiting the fundamentals of phosphorus fractionation of sediments and soils
J. Soils Sediments
Contributions from carbon and nitrogen in roots to closing the yield gap between conventional and organic cropping systems
Soil Use Manage.
Current nitrogen management status and measures to improve the intensive wheat-maize system in China
Ambio
Winter cover crop effects on soil structural stability and microbiological activity in organic farming
Biol. Agric. Hortic.
Inter-decadal variation of the summer precipitation in China and its association with decreasing Asian summer monsoon Part II: possible causes
Int. J. Climatol.
Accumulation of nitrate-N in the soil profile and its implications for the environment under dryland agriculture in northern China: a review
Can. J. Soil Sci.
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