生育期对红壤旱坡花生地氮素径流流失的影响

探明作物不同生育期的氮素流失特征,以期为红壤旱坡地氮素流失预测与有效防控提供理论依据。采用土壤水分渗漏试验装置,对自然降雨条件下赣北第四纪红壤旱坡花生地不同生育期的地表径流、渗漏水及其各形态氮素输出过程进行连续观测。结果表明:(1)红壤旱坡花生地产流主要发生在降雨量最为集中的开花下针期。渗漏水是各生育期主要的径流形式,占总径流量的64%。(2)各生育期,氮素流失的主要途径为渗漏水,主要形式为可溶性氮,占总氮(TN)流失量的54%～99%。除饱果成熟期外,各生育期渗漏水中氮素流失的主要成分为硝态氮,占TN的38%～50%。(3)地表径流和渗漏水氮素浓度总体表现为幼苗期和开花下针期较大,饱果成熟期最小,而氮素流失量则表现为开花下针期最大。因此,幼苗期和降雨量最为集中的开花下针期为防治红壤旱坡花生地氮素流失的关键时期,控制硝态氮等氮素淋溶损失是减少红壤旱坡花生地氮素流失的关键途径。

Effects of Growth Periods on Nitrogen Loss in Runoff of Peanut Land on Dry Slope of Red Soil

This study aimed to explore the characteristics of nitrogen loss in different growth periods of crops, which could provide theoretical basis for the prediction and effective control of nitrogen loss in dry sloping land of red soil. Under natural rainfall conditions, lysimeters were continuously used to collect the data about surface runoff, seepage water and nitrogen output process on dry slope of Quaternary red soil in northern Jiangxi. The results showed as follows:(1) Runoff generation of peanut land on dry slope of red soil mainly occurred at the flowering period with the most abundant rainfall. Leakage water was the main form of runoff in peanut growing period, accounting for 64% of the total runoff. (2) Leakage water was the main path of nitrogen loss in all growth periods, primarily in the form of soluble nitrogen, occupying 54% to 99% of total nitrogen (TN) loss. Nitrate nitrogen (38%~50% of TN) was the main component of nitrogen loss in seepage water during all periods except the ripening period of full fruit. (3) Nitrogen concentrations in surface runoff and seepage water in the seedling period and flowering period were larger than those in other growth periods, while the nitrogen loss in them was the largest in flowering period. Therefore, the key periods for controlling nitrogen loss in peanut land on dry slope of red soil were the seedling stage with the lowest vegetation coverage and the flowering stage with the most concentrated rainfall. Besides, the crucial way to reduce nitrogen loss in the land was controlling nitrogen leaching loss such as nitrate nitrogen.