土壤水分对玉米秸秆还田腐解率、土壤肥力及小麦籽粒蛋白质产量的影响

Influence of Soil Moisture on Decomposition of Maize Stalk,Soil Fertility and Grain Protein Yield in Winter Wheat

为提高玉米秸秆还田效果,通过防雨棚微区控水设施,研究了土壤水分对还田玉米秸秆腐解、土壤肥力及小麦籽粒蛋白质产量的影响,3个土壤水分水平分别为田间持水量的50%～55%(干旱)、60%～65%(轻旱)和70%～75%(适宜水分)。结果表明,小麦季还田玉米秸秆腐解速率表现为"快-慢-快"的变化趋势。随着土壤水分含量的增加,秸秆量减少率逐渐增加。秸秆腐解前期(0～70 d),干旱条件下秸秆量累计减少率、氮素释放率显著降低(P<0.05);成熟期,不同土壤水分条件下秸秆量累计减少率及氮素释放率分别为66.50%～69.51%和75.88%～77.31%,不同土壤水分处理间差异不显著。与播前相比,成熟期不同处理0～25 cm耕层土壤有机质含量基本表现为降低趋势,但秸秆还田(RS)处理土壤有机质含量下降幅度较对照(CK)显著降低。与CK相比,RS处理0～25 cm耕层土壤有机质含量显著提高(16.1%～17.2%);不同生育时期土壤0～25 cm耕层的碱解氮含量显著提高(11.65%～23.10%);小麦籽粒蛋白质含量略有降低,籽粒蛋白质产量显著降低(4.63%)。在秸秆还田条件下,干旱处理的小麦籽粒蛋白质含量均显著高于轻旱和适宜水分处理。综上,还田玉米秸秆的腐解和氮素释放需要较好的土壤水分条件;土壤水分适宜时进行秸秆粉碎翻压还田有利于提高土壤有机质和碱解氮含量;干旱条件下秸秆还田导致小麦籽粒产量和蛋白质产量均显著降低。

A micro-plot experiment was conducted to investigate the influence of different soil moisture on decomposition of maize stalk,soil fertility and grain protein yield in winter wheat( Triticum aestivum L.),which provided reference for improving the effect and application of maize stalk returning.The experiment was conducted under a rain proof shelter which was subjected to 50%-55%(drought,D),60%-65%(slight drought,SD) and 70%-75%(normal,N) of field moisture capacity,respectively.Two disposal patterns of maize stalks returning before wheat sowing(stalk returning,RS) and non-stalk returning as control(CK),were employed.The results indicated that the decomposition rate of maize stalk showed a trend of ‘fast-slow-fast’ during the whole growing period of winter wheat.With the increase of soil moisture content,the reduction rate of stalk residual amount increased gradually.At the beginning(0-70 d) of maize stalk returning,both mass loss rate of maize stalks and nitrogen release rate were dramatically reduced under drought conditions( P <0.05).At maturity,stalk decomposition rate and nitrogen release rate under different soil moisture content were 66.50%- 69.51% and 75.88%-77.31%,respectively,and no significant difference exist between different treatments.Content of soil organic matters within 0-25 cm soil layer of different patterns under different soil moisture contents appeares a decreasing trend from wheat seed sowing to maturity.However,the decrease rate of soil organic matter content under RS is significantly lower than that under CK.Compared to CK,soil organic matter content within 0-25 cm soil layer was significantly increased by 16.1%-17.2% and alkaline hydrolytic nitrogen content was dramatically increased by 11.65%- 23.10%.Compared with CK,wheat grain protein content under RS showed slight decrease,and grain protein yield under RS was significantly decreased by 4.63%( P <0.05).Additionally,wheat grain protein content under D treatments were dramatically increased compared with those under either SD or N treatments.It could be concluded that decomposition and nitrogen release of maize stalk returning need relatively appropriate soil moisture conditions(normal soil moisture content or even slight drought in this experiment).Stalk returning under suitable soil moisture content will help to increase the content of both soil organic matters and alkaline hydrolytic nitrogen.However,stalk returning under drought conditions,resulted in a significant reduction in grain yield and protein yield.