玉米秸秆还田和有机配施提高黑土酸中和容量

长期施用化肥导致农田黑土酸化、盐基离子耗竭、养分失衡及作物重金属污染等诸多问题。本文依托吉林公主岭国家黑土肥效监测基地25 a的施肥试验,研究了不施肥对照（C）、N、NP、NK、PK、NPK、厩肥—化肥配施（MNPK）、玉米秸秆还田（SNPK）等8个施肥处理对土壤酸中和容量（ANC）的影响,N、P、K施用量分别为165 kg hm^-2 a^-1、36 kg hm^-2 a^-1、68.5 kg hm^-2 a^-1,MNPK和SNPK处理与NPK处理为等N量。结果表明,施化肥导致表土pH下降0.37~1.39,MNPK和SNPK处理分别提高土壤pH值0.21和0.53。以pH 5.0为参比,N、NP、NK、PK、NPK各处理的酸中和容量ANC_{pH 5.0}分别为对照的42.85%、61.79%、54.05%、82.26%、63.68%;MNPK处理的ANC_{pH 5.0}是对照的1.86倍;加酸160 mmol kg^-1,SNPK处理的土壤pH值仅从7.65降至6.42,表现出极强的酸中和能力。SNPK和MNPK处理的土壤交换性盐基总量SEB分别是对照的1.37和1.14倍,土壤有机质SOM分别是对照的1.32和1.63倍,二者是提高土壤ANC主要原因。总之,有机物料添加显著提高了黑土抗酸化性能及土壤基础肥力水平,研究结果可为东北黑土区玉米秸秆还田保护性耕作及有机肥部分替代化肥实践提供长期试验的理论依据和数据支撑。

Corn stalk return and manure amendment improve acid neutralizing capacity of a black soil in Northeast China

Long-term application of chemical fertilizers can lead to soil acidification, basic cation depletion, nutrient imbalance and heavy metal pollution of crops in farmland of Black Soil regions. Based on a 25-year National Black Soil Fertilizer Efficiency Monitoring Experiment in Gongzhuling, Jilin Province, the effects of 8 different fertilization treatments on soil acid neutralizing capacity (ANC) was examined, including no fertilization (Control or C), N, NP, NK, PK, NPK, combination of farmyard manure with chemical fertilizers (MNPK), and corn stalk return (SNPK). The application rates of N, P and K were 165, 36 and 68.5 kg hm^-2 a^-1, respectively, and N input was the same among NPK, MNPK and SNPK treatments. Results showed that chemical fertilizer application decreased topsoil pH by 0.37-1.39, while MNPK and SNPK treatments increased soil pH by 0.21 and 0.53, respectively. Acid neutralizing capacity as soil pH dropped to 5.0 (ANC_{pH 5.0}) of N, NP, NK, PK and NPK treatments was 42.85%, 61.79%, 54.05%, 82.26% and 63.68% of the Control, respectively, while the ANC_{pH 5.0} of MNPK treatment was 1.86 times of the Control. With 160 mmol kg^-1 H⁺ addition, the pH of SNPK-treated soil only decreased from 7.65 to 6.42, showing an extremely strong acid neutralizing capability. Soil exchangeable base cations were 1.37 and 1.14 times, while soil organic matters were 1.32 and 1.63 times, in SNPK and MNPK treatments as much as that in the Control, respectively, which are two main factors in improving soil ANC. In brief, the addition of organic materials significantly improved the anti-acidification properties and soil basic fertility level of the black soil. The results could provide theoretical basis and data support with long-term experiment evidence for the practices of conservation tillage with corn stalk return and chemical fertilizers partly substituted by farm-yard manure in black soil regions of Northeast China.