湘北双季稻区种植翻压紫云英的氮肥减施效应

王慧; 周国朋; 常单娜; 高嵩涓; 刘蕊; 廖育林; 鲁艳红; 曾闹华; 聂军; 曹卫东

doi:10.11674/zwyf.2021292

湘北双季稻区种植翻压紫云英的氮肥减施效应

Nitrogen reduction effects in double rice by planting and returning Chinese milk vetch to the field in Northern Hunan Province

摘要

摘要:
目的评价双季稻区冬闲田种植翻压紫云英模式下减施不同量氮肥对水稻产量和土壤理化性状的影响，为湘北稻区双季稻减肥增效提供理论依据。
方法定位试验始于2009年，设置不施肥(CK)，常规施肥(N100)，种植翻压紫云英配合早稻及晚稻均减施常规量氮肥的0%、20%、40%、60% (MvN100、MvN80、MvN60、MvN40)，以及单独种植利用紫云英(Mv) 处理，共7个处理。测定各处理水稻产量、氮磷钾吸收量、土壤理化性质及6种碳氮磷循环相关水解酶(α-葡萄糖苷酶、β-纤维二糖苷酶、β-葡萄糖苷酶、β-木糖苷酶、亮氨酸氨基肽酶和碱性磷酸酶)活性。
结果与N100处理相比，种植利用紫云英有明显的增产和节肥效果，其中，MvN100处理全年稻谷增产10.2%，MvN40处理全年稻谷不减产。在早稻季，种植利用紫云英条件下减施氮肥，在保证土壤全氮稳定的前提下显著提高了水稻地上部氮吸收量和利用效率。与N100比较，紫云英配合氮肥减施常规量的0～60%，水稻地上部氮吸收量显著增加16.6%～43.4%，同时氮肥利用率提高8.4%～37.8%。单独紫云英处理的早晚稻土壤碳、氮、磷循环相关水解酶活性最高，与N100处理相比，MvN80和MvN60处理下α-葡萄糖苷酶、β-纤维二糖苷酶、β-葡萄糖苷酶和β-木糖苷酶活性显著提高。相关性分析结果表明，土壤有效磷、速效钾含量与水稻产量显著相关，聚合增强树分析(ABT)进一步证实土壤有效磷对早晚稻产量贡献率最大，分别是30.4%和50.2%。
结论连续10年的试验充分证明，在种植翻压紫云英条件下，早稻季减施常规量氮肥60%、晚稻季减施常规量氮肥40%，可提高水稻氮、磷、钾养分吸收量和土壤酶活性，可满足水稻正常生产。供试土壤丰富的有效磷和速效钾含量是减施氮肥确保水稻产量的重要因素。

Abstract:
Objectives To evaluate the effects of reducing the amount of nitrogen fertilizer on rice yield and soil properties under the mode of planting and returning Chinese milk vetch (Astragalus sinicus L., CMV) to the field in the following rice season. The study aims to provide a theoretical basis for environmentally friendly and efficient double-cropping rice production in Northern Hunan Province.
Methods The long-term experiment, early rice–late rice–CMV rotation, started in 2009. There were 7 treatments, including no fertilization (CK), conventional fertilization (N100), fertilization combined with N reduction at 0, 20%, 40%, and 60% (MvN100, MvN80, MvN60, MvN40) of conventional N rate and CMV alone (Mv). Rice yield, N, P, and K absorption, soil physicochemical properties and six hydrolase activities related to C, N, and P cycle (α-glucosidase, β-cellobiosidase, β-glucosidase, β-xylosidase, L-leucine aminopeptidase, alkaline phosphomnoesterase) were determined.
Results Compared with the N100, all the Mvs increased yield and saved fertilizer, with the highest yield increase recorded in MvN100 (10.2% in the whole year). In the early rice season, planting and returning CMV (P<0.05) improved the N absorption and utilization efficiency of rice to ensure the stability of soil total N. Compared with N100, CMV combined with 0–60% less N fertilizer increased N uptake by 16.6%–43.4% and N use efficiency by 8.4%–37.8%. The hydrolases activities related to C, N, and P cycling were the highest under Mv treatments in the whole year. Compared with N100, MvN80 and MvN60 (P < 0.05) increased α-glucosidase, β-cellobiosidase, β-glucosidase, and β-xylosidase activity. The results of correlation analysis showed that available soil P and K (P < 0.05) correlate with rice yield. Aggregation enhancement tree analysis (ABT) further confirmed that the contribution rate of available soil P to early and late rice yield was 30.4% and 50.2%, respectively.
Conclusions The 10-years field experiment proved that planting and turnover of CMV could replace 60% N fertilizer in early rice and 40% in late rice without impacting rice yields, due to increased N, P, and K accumulation in rice and soil enzyme activities. The experimental soil’s high available P and K content greatly contribute to the replacement ratio mentioned above.

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