Long-term green manuring enhances crop N uptake and reduces N losses in rice production system
Introduction
Green manuring is a traditional cultivation practice that has played an essential role in the improvement of soil fertility and crop yield in the long history of agricultural production in China (Cao et al., 2017). Green manure has attracted considerable research attention in the 21st century because it can achieve dual goals of food security and green development of agriculture. Several field experiments were recently conducted to examine effects of green manuring on crop growth and N losses (Xie et al., 2016, Mohanty et al., 2020). The results showed that green manuring is a promising method for reducing chemical N fertilizer input and reactive N losses in the environment while maintaining crop yield (Gao et al., 2020, Fontaine et al., 2020).
Milk vetch (Astragalus sinicus L.) is a typical leguminous green manure used in the rice system, grown during fallow season, and incorporated into the soil at their full-bloom stage before transplanting rice. The fixed atmospheric N is released into the soil as the mineral N form with the decomposition of milk vetch. The enhancement of the soil N supply via milk vetch incorporation can satisfy the N requirement of the subsequent rice. Based on 11 field experiments in south China, researchers found that milk vetch can replace 20–40% of chemical N fertilizer while slightly increasing rice yield compared with conventional chemical N management practices (Gao et al., 2020). The cultivation and utilization of milk vetch showed high potential in reducing the chemical N input and N losses while ensuring rice yield (Zhao et al., 2015, Yao et al., 2017). Previous studies demonstrated that green manuring can substantially reduce N losses through leaching (Zhang et al., 2016), runoff (Zhao et al., 2013), ammonia volatilization (Bai et al., 2015), and N2O emission (Mohanty et al., 2020). However, long-term studies are needed to ensure the effectiveness of milk vetch incorporation as an alternative approach for reducing chemical N fertilizer input and N losses while maintaining rice yield (Lee et al., 2010).
Quantifying N mineralization from green manure is a key process in evaluating crop N use efficiency and developing optimal management practices for rice–green manure systems. However, direct in situ measurement of N mineralization is labor-intensive, time-consuming, and unreliable. Process-based models provide a powerful method for quantifying effects of various field management practices on N fates and crop growth (Mary et al., 1999, Hansen et al., 2012, Liang et al., 2019). Constantin et al. (2011) used the LIXIM model to quantify cumulative impacts of green manure incorporation on net N mineralization and N fates; the results showed that green manuring enhances soil N mineralization (9–26 kg N ha−1 yr−1) and crop N uptake. Clivot et al. (2017) successfully quantified in situ net N mineralization from soil organic matter in 65 arable bare soils in France using the same model. Yin et al. (2020) calculated the soil N mineralization rate and N fates in a 34-year crop rotation field and reported that the model captures long-term effects of green manuring on N mineralization and N fates. The LIXIM model was recently integrated into the soil water heat carbon nitrogen simulator (WHCNS) model to improve the simulation of soil net N mineralization and N fates of the rice system, and the integrated model (WHCNS_LIXIM) can be used to evaluate water and N use efficiencies of different rice production systems in China (Liang et al., 2019). The integrated model showed a good performance in modeling N fates under different N management practices for rice system (Shi et al., 2020, Liang et al., 2021). Therefore, the WHCNS_LIXIM model was adopted in this study to estimate soil net N mineralization and N fates of the rice–green manure system.
This study aims to (i) examine effects of green manure substitution on soil N supply and crop growth on the basis of three long-term field experiments; (ii) test the performance of the WHCNS_LIXIM model in simulating soil N dynamics, crop N uptake, and crop growth for the rice–green manure system; and (iii) evaluate effects of green manure substitution on N mineralization and N losses.
Section snippets
Site description
The three field experiment sites are located in a major rice production area of south China (Table 1). Xinyang site (32.13° N, 114.08° E) in Henan Province belongs to the subtropical–warm transitional zone, and Yujiang (28.20° N, 116.81° E) and Gaoan (28.25° N, 115.12° E) sites in Jiangxi Provance are in the humid subtropical monsoon climate zone. Annual mean temperature (or precipitation) is 16.6 °C (1776 mm), 17.6 °C (1789 mm), and 17.7 °C (1560 mm) for Xinyang, Yujiang, and Gaoan sites,
Crop dry matter and grain yield
Crop dry matter (DM) at different stages of rice growth is presented in Table 5. Differences in DM among various treatments at all sites were negligible, and the average DM at maturity was 19,606, 13,881, and 10,256 kg ha−1 for Xinyang, Yujiang, and Gaoan sites, respectively (Table 5). Crop yield of green manure-incorporated treatments demonstrated no significant differences with the F100 treatment at Xinyang and Gaoan sites. The incorporation of green manure had no significant impact on DM but
Effects of green manure incorporation on crop growth and N uptake
Gao et al. (2020) used datasets from 11 field experiments in south China and revealed that the incorporation of milk vetch saves 20–40% of chemical N fertilizer and slightly increases crop yield compared with conventional chemical N management practices. Lee et al. (2010) evaluated effects of different application rates of milk vetch on rice yield and crop N uptake and showed that the significant increase of rice yield from the increase of milk vetch application from 0 t ha−1 to 20 t ha−1 is
Conclusion
The results of three long-term field experiments showed that green manure-applied treatments enhance SMN from 27.4% to 94.9% at the jointing stage and from 1.0% to 45.0% at the maturity stage compared with the use of urea alone. The crop N uptake increased with the increase of green manure application rates, and the average crop N uptake increased from 147.8 kg N ha−1 to 254.6 kg N ha−1 when the green manure application rate increased from 0 t ha−1 to 45 t ha−1. The WHCNS_LIXIM model
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgment
The study was funded by the National Key Research and Development Program of China (2021YFD1700200), the National Natural Science Foundation of China (No. 42007071), the Earmarked Fund for Modern Agro-industry Technology Research System-Green Manure (CARS-22).
References (37)
- et al.
Integrated application of February Orchid (Orychophragmus violaceus) as green manure with chemical fertilizer for improving grain yield and reducing nitrogen losses in spring maize system in Northern China
J. Integr. Agric.
(2015) - et al.
Nitrogen mineralization of vegetable root residues and green manures as related to their (bio)chemical composition
Eur. J. Agron.
(2004) - et al.
Quantifying in situ and modeling net nitrogen mineralization from soil organic matter in arable cropping systems
Soil Biol. Biochem
(2017) - et al.
Simulating the effects of conventional versus conservation tillage on soil water, nitrogen dynamics, and yield of winter wheat with RZWQM2
Agric. Water Manag.
(2020) - et al.
Cover crop and cereal straw management influence the residual nitrogen effect
Eur. J. Agron.
(2020) - et al.
Effect of reduced mineral fertilization (NPK) combined with green manure on aggregate stability and soil organic carbon fractions in a fluvo-aquic paddy soil
Soil Till. Res.
(2021) - et al.
Short term effects of different green manure amendments on the composition of main microbial groups and microbial activity of a submerged rice cropping system
Appl. Soil Ecol.
(2020) - et al.
Effect of Chinese milk vetch (Astragalus sinicus L.) as a green manure on rice productivity and methane emission in paddy soil
Agric. Ecosyst. Environ.
(2010) - et al.
Effects of long-term chemical fertilization and organic amendments on dynamics of soil organic C and total N in paddy soil derived from barren land in subtropical China
Agric. Ecosyst. Environ.
(2010) - et al.
Ground cover rice production system reduces water consumption and nitrogen loss and increases water and nitrogen use efficiencies
Field Crop. Res.
(2019)
Modeling water consumption, N fates, and rice yield for water-saving and conventional rice production systems
Soil Till. Res.
Meta-analysis of green manure effects on soil properties and crop yield in northern China
Field Crop. Res.
Modelling N mineralization from green manure and farmyard manure from a laboratory incubation study
Ecol. Model.
Impact of integrated nutrient management options on GHG emission, N loss and N use efficiency of low land rice
Soil Till. Res.
Soil inorganic N availability: effect on maize residue decomposition
Soil Biol. Biochem.
Modelling temperature and moisture effects on C–N transformations in soils: comparison of nine models
Ecol. Model.
Rosetta: a computer program for estimating soil hydraulic parameters with hierarchical pedotransfer functions
J. Hydrol.
Exploring optimal nitrogen management strategies to mitigate nitrogen losses from paddy soil in the middle reaches of the Yangtze River
Agric. Water Manag.
Cited by (20)
Exploring site-specific N application rate to reduce N footprint and increase crop production for green manure-rice rotation system in southern China
2023, Journal of Environmental ManagementSouthern China can produce more high-quality rice with less N by green manuring
2023, Resources, Conservation and RecyclingThe potential of green manure to increase soil carbon sequestration and reduce the yield-scaled carbon footprint of rice production in southern China
2023, Journal of Integrative Agriculture