提升雨养夏玉米—冬小麦两熟体系生产力和土壤硝态氮累积的最优耕作模式

【目的】研究耕作模式对旱地雨养夏玉米–冬小麦(以下简称玉–麦)两熟体系生产力的影响，并对深松、翻耕在轮耕模式中的作用进行评价。【方法】定位试验于2015—2021年在中国农业科学院洛阳旱农试验基地进行。设置夏免耕秋免耕(SNAN)、夏深松秋免耕(SSAN)、夏免耕秋3年免耕1年翻耕(SNA3N1P)、夏深松秋3年免耕1年翻耕(SSA3N1P)和传统夏秋季均翻耕(CT) 5种耕作模式，调查了玉米、小麦的产量和水分利用效率，2020年测定了玉米收获期0—40 cm土层土壤容重、养分含量和酶活性，以及2019—2020年度小麦收获期0—380 cm土层的硝态氮累积量。【结果】1)与CT处理相比，SNAN、SSAN、SNA3N1P和SSA3N1P处理的玉米、小麦和周年产量分别显著提高了28.4%～33.5%、23.7%～25.0%和27.1%～30.3%，水分利用效率分别显著提高了19.6%～39.2%、20.2%～29.3%和29.5%～34.5%,0—5 cm和20—40 cm土层土壤容重显著降低，0—5 cm土层的有机质含量以及0—40 cm多数土层的全氮、有效磷、速效钾含量和脲酶、蔗糖...

Optimum tillage pattern with high crop productivity and soil nitrate-N accumulation in rain-fed summer maize and winter wheat double cropping system

  【Objectives】  We compared the effects of different tillage patterns on crop productivity and nitrate-N accumulation of soil under rain-fed condition, for high yield and less N leaching risk.   【Methods】  From 2015 to 2021, a field study was conducted at the Luoyang Dry Farming Experimental Plot of the Chinese Academy of Agricultural Sciences. The cropping system was summer maize-winter wheat. The experiment included five treatments: no tillage in both summer and autumn (SNAN), subsoiling in summer and no tillage in autumn (SSAN), no tillage in summer plus consecutive 3-year-no-tillage-1-year plough in autumn (SNA3N1P), subsoiling in summer plus consecutive 3-year-no-tillage-1-year plough in autumn (SSA3N1P), and conventional plough after wheat and maize harvest (CT). The crop yield and water use efficiency were investigated in 2015–2021. The bulk density, nutrient content, and enzyme activity in the 0–40 cm soil layer were determined at maize harvest in 2020. The nitrate-N accumulation in the 0–380 cm soil layer was investigated at wheat harvest in 2019–2020.  【Results】  1) Compared with CT, SNAN, SSAN, SNA3N1P, and SSA3N1P significantly increased maize yield by 28.4%–33.5%, wheat yield by 23.7%–25.0%, and whole year yield by 27.1%–30.3%; increased maize water use efficiency (WUE) by 19.6%–39.2%, wheat WUE by 20.2%–29.3%, and whole year WUE by 29.5%–34.5%; decreased soil bulk density at 0–5 cm and 20–40 cm soil layer significantly; increased organic matter (OM) at 0–5 cm soil layer and total N (TN), available P (AP), readily available K (AK) content; and increased surcease and urease activity at most measured layer in 0–40 cm soil profile; meanwhile, the nitrite-N accumulation was increased by 44.3%–104.8% in 0–80 cm soil profile but decreased by 22.1%–34.1% in 120–380 cm soil profile. 2) Compared with no tillage in summer (namely SN), subsoiling in summer (namely SS) did not affect the crop yield, but significantly decreased maize WUE, increased OM at 10–20 cm soil layer, TN in 0–20 cm profile, AP at 0–5 cm and 10–20 cm soil layer, AK at 10–20 cm soil layer, urease activity in 5–40 cm profile, sucrase activity in 0–40 cm profile; SS increased soil bulk density at 20–40 cm layer and nitrite-N accumulation at 0–380 cm soil profile. 3) Compared with no tillage in autumn (AN), A3N1P significantly decreased TN and AP contents at 0–5 cm soil layer, but increased OM in 5–20 cm, AK in 5–40 cm soil profile, and increased urease and surcease activity in 0–40 cm soil profile. Compared with AN, A3N1P significantly increased the 6-year-average WUE of wheat by7.1% under SN, while decreased nitrate-N in 0–380 cm soil profile by 12.4% under SS. 4) Comprehensively, SSA3N1P had significant effect on crop yield and WUE, but it had the best soil properties among the five treatments, and exhibited the function of increasing nitrite-N in root layer (0–80 cm) and decreasing it in deeper soil layer (120–380 cm).   【Conclusions】  Subsoiling in summer exhibited better effect than no tillage in summer in improving soil properties. Consecutive 3 years of no tillage and following 1 year plowing (A3N1P) also performed better than no tillage in autumn. The tillage pattern of subsoiling in summer plus consecutive 3-year-no-tillage-1-year plough in autumn (SSA3N1P) was best in improving soil properties, crop productivity and optimizing soil nitrate-N, and therefore was recommend as an alternative tillage pattern in rainfed maize-wheat double cropping system.