水分对河西青贮玉米土壤化学计量比及稳态性的影响

Effects of water treatment on stoichiometric ratio and homeostasis of silage corn soil in Hexi

为探究河西灌溉区农田生态系统土壤养分限制及其循环规律,明确不同水分处理下青贮玉米植株与土壤的稳态性特征,以甘肃省河西灌溉区W0(传统灌水)、W1(节水10%)、W2(节水20%)、W3(节水30%)4种灌水处理的青贮玉米为研究对象,分析不同灌水处理下土壤、植株有机碳(OC,Organic Carbon)、全氮(TN,Total Nitrogen)、全磷(TP,Total Phosphorus)含量及其生态化学计量特征变化和植株与土壤间的内稳性特征。结果表明:(1)不同灌水处理下青贮玉米土壤OC、TN、TP含量均在0~10 cm土层达到最高值。(2)4种灌水处理下,植株器官养分含量在W0灌水处理下显著升高;在0~30 cm土层土壤OC、TN、TP含量在W1灌水处理下最高,且TN、TP显著高于其余灌水处理6.66%~26.17%、4.67%~19.21%;随灌水量减少土壤及植株养分降低显著。(3)土壤、植株C∶N、C∶P、N∶P值变化范围分别为3.60~61.2、4.39~53.9、1.01~1.24,其中,土壤C∶N值在各土层及不同灌水处理下较为稳定,叶片(11.9)、根(7.58)的N∶P值均小于植株氮限制的阈值(14),说明植株生长受到氮元素的限制。(4)4种灌水处理下,植株(根、叶片)OC、TP元素及其化学比值稳态性均呈现绝对稳定状态,但在W2处理下叶片N∶P稳态性表现出敏感状态。可见,在河西灌溉区,节水10%不仅有利于青贮玉米土壤养分的存留及保持作物生长的稳定适应能力,也可达到节水目的,进而缓解水资源紧缺的现状。

A study was conducted using irrigation treatments and changes in soil and plant carbon(OC), nitrogen(TN), and phosphorus(TP) stoichiometry and homeostasis were investigated to explore the soil nutrient limitation in farmland ecosystems in the Hexi irrigation area. The following results are presented.(1) The OC, TN, and TP concentrations of silage maize soils under different irrigation treatments reached the highest values in 0-10 cm.(2) Among four irrigation treatments, the nutrient content of plant organs was the highest under W0irrigation.However, at 0-30 cm soil layers, the values of soil OC, TN, and TP concentrations were the highest under W1irrigation treatment(i. e., traditional irrigation), soil TN and TP contents were more than those under other irrigation treatments(6.66%-26.17% and 4.67%-19.21%, respectively), and the decrease in soil and plant nutrients was more significant than that in irrigation water amount.(3) The ranges of C:N, C:P, and N:P ratios in soil and plants were at 3.60-61.2, 4.39-53.9, and 1.01-1.24, respectively. Soil C:N ratios were relatively stable among three soil layers and different irrigation treatments. The N:P ratios of leaves(11.9) and roots(7.58) were less than the threshold of plant N limitation(14), indicating that plant growth was limited by N.(4) Among four irrigation treatments, corn OC and TP and their ratios remained stable. However, the leaf N: P homeostasis was more sensitive to W2treatment(20% water-saving irrigation) than to W0treatment. Thus, 10% water-saving treatment in the Hexi irrigation area might be beneficial to the retention of soil nutrients in silage corn and maintains the stable adaptability of crop growth, realizing the purpose of water-saving and alleviating the current water scarcity situation.