南疆滴灌棉田土壤速效养分时空分布特征

Spatial and Temporal Distribution Characteristics of Soil Available Nutrient in Drip-irrigation Cotton Field of Southern Xinjiang

为研究滴灌棉田土壤速效养分的分布特征,对棉花整个生育期的土壤养分状况进行分析,揭示滴灌棉田土壤速效养分的分布特征及对产量及其构成因素的影响。结果表明：高产田、中产田、低产田3个处理土壤碱解氮的变化趋势相同,随深度增加均呈下降的趋势,40-60cm土层的碱解氮质量分数的曲线较为平缓,3个处理0-60cm垂直变异随生育期的推进呈先增大后减小的趋势,由于棉株从苗期进入蕾期对氮素的需求量较大,碱解氮质量分数会急剧降低;而进入铃期到吐絮期后,棉花对氮的需求量逐渐减少,其质量分数又有所回升。各处理土壤速效磷质量分数的时空变化趋势基本一致,均表现先上升后下降的趋势。滴灌棉田棉花的磷素需求量在出苗后1-40d逐渐减小,土壤速效磷质量分数呈上升趋势;40d后,棉花进入蕾期,棉株对磷素的吸收量增大,土壤速效磷质量分数明显降低,盛花期后开始回升,直至吐絮期开始平缓下降至稳定;各处理土壤速效钾质量分数随生育期的变化表现为较平缓的趋势。

To determine soil nutrient characteristics is the precondition of scientific fertilization in cotton field, which is also the foundation of cotton field fertility improvement. This study analyzed field soil nutrients during whole growth period of cotton, and revealed the distribution characteristics of available nutrient in cotton drip-irrigation soil and its influence on yield and yield components. The results showed that a similar downward the trend of soil alkaline nitrogen with the increase of soil depth was detected in three treatments of high yield field,medium yield field,and low yield field. The mass fraction of alkali-hydrolyzable nitrogen flatted at 40-60 cm soil layer, and the vertical variation at 0- 60 cm soil layers in three treatments was enlarged firstly and narrowed subsequently along with the growth period,which was ascribed to high demand of cotton plants for nitrogen from seedling stage to bud stage,alkali-hydrolyzable nitrogen in soil reduced sharply; but after entering the bell stage, cotton reduced the demand for nitrogen gradually,the mass fraction of alkali-hydrolyzable nitrogen recovered as well. The processing of soil available phosphorus mass fraction changed with the similar up-and- down trend in space and time. The demand of drip irrigated cotton for phosphorus decreased gradually in 1--40 d,and the soil available phosphorus mass fraction was rising; entering the blooming stage after 40 d,cotton increased the uptake of phosphorus, which led to significant decrease of soil available phosphorus mass fraction. The mass fraction of available phosphorus rebounded after full-bloom stage,and then fell to stable gently until the boll opening period. The change of soil available potassi- um mass fraction in each treatment presented a flat curve during growth period. These results can be used as a theoretical basis of reasonable fertilization in drip-irrigated cotton field.