秸秆还田结合氮肥运筹管理对白土稻田土壤理化性状的影响

李录久; 吴萍萍; 王家嘉; 耿言安; 姚文麒

doi:10.11674/zwyf.15351

秸秆还田结合氮肥运筹管理对白土稻田土壤理化性状的影响

Effect of wheat straw addition with nitrogen application on physical-chemical properties of white paddy soil

摘要

摘要:
目的研究不同氮肥基追比例运筹方式下小麦秸秆直接还田对白土稻田理化性状和水稻产量的影响，为江淮低产白土改良培肥提供科学依据。

方法采用两因素裂区试验，因素一为小麦秸秆 (S) 直接还田 (3000 kg/hm²)和小麦秸秆不还田；因素二为氮肥基肥-分蘖肥-穗肥施用比例。设 3 种基施:分蘖肥:穗肥比例 (80–0–20、60–20–20 和 40–30–30)，共 6 个处理，分别为 N_80–0–20、N_80–0–20 + S、N_60–20–20、N_60–20–20 + S、N_40–30–30 和 N_40–30–30 + S。水稻收获期采集 0—20 cm 代表性土壤样品分析理化性状, 包括 pH、有机质、氮磷钾养分含量、阳离子交换量 (CEC)、团聚体结构和容重，测定水稻籽粒产量。

结果与不还田相比，3 种氮肥运筹方式下，小麦秸秆还田土壤 pH 均明显升高，以 40–30–30 方式升高幅度最大，增加达到显著水平；无论是否实施麦秸还田，不同氮肥运筹方式间土壤 pH 差异不显著。土壤有机质、有效磷、速效钾含量明显提高, CEC 增大。土壤中 >5 mm 和 1～0.25 mm 两个粒径机械稳定性及水稳定性大团聚体数量增多，< 0.25 mm 小团聚体数量减少，团聚体质量提高；土壤容重下降，总孔隙度增加，白土淀浆板结的不良物理性状改善，氮肥 60–20–20 运筹方式下秸秆直接还田改良培肥白土效果最好。4 年 4 地试验，与无秸秆的对照相比，3 种氮肥运筹方式下，水稻籽粒产量分别提高 10.2%～23.4%、0.8%～5.5%、4.9%～6.4% 和 6.4%～9.6%，平均增产 16.2%、3.6%、5.5% 和 8.1%，N_60-20-20 + S 处理水稻籽粒产量最高。

结论综合水稻产量、秸秆还田后土壤养分状况、团聚体稳定性和容重、孔隙度等物理性状，安徽省江淮丘陵白土单季稻区，水稻基肥–分蘖肥–穗肥施用比例 60–20–20 运筹方式下，配合实施小麦秸秆直接还田，能有效改良培肥低产白土稻田，提高水稻产量。

Abstract:
Objectives The effects of wheat straw directly returning to paddy soil under different ratios of basal-topdressing of nitrogen (N) applications on soil physical-chemical properties and rice yield were studied to provide a scientific base for fertility improvement of low-yield white paddy soil in Jianghuai hilly lands.

Methods Two factor split field experiments were conducted concussively for four years. Wheat straw returning (3000 kg/hm²) or not was the main factor; N fertilizer was divided into three parts and applied in basal, tillering stage and heading stage 80–0–20, 60–20–20, and 40–30–30. The treatments were coded as N_80–0–20, N_80–0–20 + S, N_60–20–20, N_60–20–20 + S, N_40–30–30 and N_40–30–30 + S. Samples of 0–20 cm topsoil were collected to analyze soil physical-chemical properties, aggregates composition and bulk density. Rice yields were investigated.

Results Compared with no wheat straw returning, wheat straw returning improved soil pH effectively under the three N ratios. Under the N ratio of 40–30–30, the soil pH was significantly increased, from acidic and slightly acidic to slightly acidic and neutral, respectively. The soil organic matter, available P, K contents and CEC were also increased significantly with the returning of wheat straw. The contents of >5 mm and 1–0.25 mm mechanical-stable and water stable aggregates were increased, and micro aggregates (< 0.25 mm) were reduced, which indicated the improvement of soil aggregate quality. Soil bulk density was decreased, and total porosity was increased which showed the adverse physical properties of white soil were improved. Straw addition under the N application ratio of 60–20–20 showed the best effect on the improvement of white soil. Rice grain yields in four experimental sites under three N application ratios were increased by 10.2%–23.4%, 0.8%–5.5%, 4.9%–6.4% and 6.4%–9.6%, with the mean of 16.2%, 3.6%, 5.5% and 8.1%, respectively, the N_60–20–20 + S treatment obtained the highest grain yield.

Conclusions Considering the rice grain yield, soil nutrient contents, aggregate stability, bulk density and porosity, N application ratio of 60–20–20 combined with wheat straw directly returning to field can effectively improve the fertility of low-yield white paddy soil, and increase rice yield in Jianghuai hilly lands under single-rice cropping system in Anhui Province.

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