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Acta Prataculturae Sinica ›› 2026, Vol. 35 ›› Issue (10): 61-78.DOI: 10.11686/cyxb2025443

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Optimization of alfalfa pasture planting patterns and nitrogen fertilizer management to reduce greenhouse gas emissions

Min-hua YIN1(), Wen-jing CHANG1, Jian-xin YIN2, Ya-ya DUAN1, Hai-yan LI1, Yan-biao WANG1, Yan-xia KANG1(), Yan-lin MA1, Ya-yu WANG1, Guang-ping QI1   

  1. 1.College of Water Resources and Hydropower Engineering,Gansu Agricultural University,Lanzhou 730070,China
    2.Zhejiang Institute of Quality Sciences,Hangzhou 310018,China
  • Received:2025-10-23 Revised:2026-01-12 Online:2026-10-20 Published:2026-09-09
  • Contact: Yan-xia KANG

Abstract:

Agricultural production is a significant contributor to global greenhouse gas emissions. Alfalfa (Medicago sativa) is the world’s most widely cultivated forage crop, and it fixes nitrogen via its root nodules. However, in intensive production systems targeting high yields and quality, this crop is often supplied with nitrogen fertilizers, and this impacts greenhouse gas emissions. Optimizing planting management practices is an effective approach to mitigate greenhouse gas emissions from alfalfa fields. In this study, we analyzed the effects of planting patterns and nitrogen management on CO2, CH4, and N2O emissions from alfalfa fields. We conducted a field experiment to analyze the effects on greenhouse gas emissions of three planting patterns (flat planting, FP; ridge-furrow planting with biodegradable film mulching over the ridge, BM; ridge-furrow planting with plastic film mulching over the ridge, PM), two types of nitrogen fertilizer (urea, U; controlled-release nitrogen fertilizer, C), and four nitrogen application levels (0, 80, 160, 240 kg·ha-1). The results show that alfalfa fields served as a net source of CO2 and N2O emissions and a sink for CH4 absorption. Compared with application of urea, application of controlled-release nitrogen fertilizer significantly reduced cumulative CO2 and N2O emissions while increasing cumulative CH4 uptake. Cumulative CO2 emissions, N2O emissions, and CH4 uptake all increased with increasing nitrogen application levels, with the largest increases in the PM treatment, followed by the BM treatment, and then the FP treatment. Alfalfa yields in the BM and PM treatments were 43.56% and 30.07% higher, respectively, than that in the FP treatment. Alfalfa yields were 8.46% higher in the controlled-release nitrogen fertilizer treatments than in the urea treatments. The highest yield (24.83 t·ha-1) was in the treatment combining 160 kg·ha-1 controlled-release nitrogen fertilizer and biodegradable mulch film on ridges, representing a 97.11% increase compared with the yield in the unmulched, nitrogen-free treatment. The global warming potential (GWP) and greenhouse gas emission intensity (GHGI) were 12.26% and 15.04%, lower, respectively, in the controlled-release nitrogen fertilizer treatment than in the urea treatment. The GWP in the BM treatment was 15.28% lower than that in the PM treatment, and 15.12% higher than that in the FP treatment. The lowest GHGI was in the BM treatment, and was 11.84% lower than that in the PM treatment and 17.18% lower than that in the FP treatment. In summary, under these conditions, application of 160 kg·ha-1 controlled-release nitrogen fertilizer combined with ridge-covered biodegradable mulch (BMC2 treatment) is the recommended cropping management system for increasing alfalfa yields and reducing greenhouse gas emissions in the Gansu Yellow River irrigation district and similar ecological zones.

Key words: controlled-release nitrogen fertilizer, biodegradable film, greenhouse gas emission, planting and management pattern, alfalfa