长期增施有机肥对氢氧同位素分布与小麦水分利用的影响

Effects of Long-term Application of Organic Fertilizer on Hydrogen and Oxygen Isotopic Distribution and Wheat Water Utilization

摘要:

为探明长期增施有机肥对土壤水分分布与水分利用的作用机理，采用室内分析与田间试验相结合，研究了长期增施有机肥和单施化肥对土壤水稳性大团聚体含量、土壤有机碳含量、饱和导水率、氢氧同位素分布、小麦光合生理特征及水分利用的影响。结果表明：增施有机肥显著提高土壤大团聚体含量、土壤有机碳含量和土壤饱和导水率，土壤结构稳定性明显提高。随土层加深，氢氧同位素丰度表现为逐渐降低趋势。在拔节期，长期单施化肥主要利用0~60cm土层水分，长期增施有机肥主要利用0~20cm土层水分，而二者0~20cm土层水分贡献率明显高于其他土层，达50%以上。在抽穗期，长期单施化肥和增施有机肥均主要利用0~20cm土层水分，且该土层水分贡献率仍超过50%。到灌浆期，长期单施化肥仍主要利用0~20cm土层水分。而长期增施有机肥主要利用20~40cm土层水分，其贡献率达50.2%。随小麦生育期推进，不同施肥措施土壤储水量均呈逐渐降低趋势。长期增施有机肥较单施化肥更利于降低小麦生长前期土壤水分无效损耗，提高土壤储水量，进而促进小麦生长后期水分供应。同时，与单施化肥相比，长期增施有机肥更利于提高小麦不同生育期的光合速率、气孔导度及叶片水分利用效率。随小麦生育期推进，其地上生物量逐渐增加且增施有机肥大于单施化肥。长期增施有机肥显著提高了小麦产量和水分利用效率。相关分析表明，在小麦生长过程中，拔节期40~60cm、80~100cm和灌浆期20~80cm土层水分供应更利于提高小麦产量，而拔节期40~60cm和80~100cm、抽穗期60~100cm、灌浆期20~40cm和60~80cm土层水分供应对水分利用效率的提高更为有利。综上，长期增施有机肥改善了土壤结构，增强了降水在土壤中的蓄、保、用能力，改善了小麦光合生理特性，促进了增产与节水增效。

Abstract:

An indoor and a field experiment were conducted to study the water-stable large aggregates, soil organic carbon content, saturated hydraulic conductivity, hydrogen isotope distribution, physiological characteristics of wheat photosynthesis and water utilization under long-term application of organic fertilizer and chemical fertilizer, thus ascertaining soil moisture distribution and water use mechanism of long-term application of organic fertilizer. The results showed that the organic fertilizer significantly increased the proportion of soil macro-aggregate, soil organic carbon content, saturated hydraulic conductivity, and thus led to the high stability of soil structure. The abundance of hydrogen and oxygen decreased gradually with the deepening of the soil layer. In the jointing period, the long-term application of chemical fertilizer mainly used the water in 0~60cm soil layer, and the yield of organic fertilizer mainly used the water of 0~20cm soil layer, while the contribution rate of soil moisture of 0~20cm soil layer was significantly higher than that of other soil layers, reaching more than 50%. In the heading period, the long-term application of chemical fertilizer and organic fertilizer mainly used the water in 0~20cm soil layer, and the contribution rate of soil moisture in this soil layer was still more than 50%. In the filling period, the long-term application of chemical fertilizer mainly used the water in 0~20cm soil layer. The long-term application of organic fertilizer mainly used the water in 20~40cm soil layer, and its contribution rate reached 50.2%. With the advancement of wheat growth period, the soil water storage decreased gradually. Long-term application of organic fertilizer was more conducive to reducing the ineffective loss of soil water in the early stage of wheat growth, which improved the soil water storage, and then promoted the supply of water in the late stage of wheat growth. Compared with application of chemical fertilizer, long-term application of organic fertilizer was more conducive to improving the photosynthetic rate, stomatal conductivity and leaf water use efficiency of wheat in different growth periods. With the advancement of wheat growth period, its aboveground biomass gradually increased and above-ground biomass of organic fertilizer was higher than that of chemical fertilizer. Ultimately, long-term application of organic carbon content significantly improved wheat yield and water use efficiency. Corcorrelation analysis showed that the water supply of 40~60cm and 80~100cm soil layers at jointing stage, and 20~80cm soil layer at filling stage of wheat were more conducive to improving wheat yield, while soil supply of 40~60cm, 80~100cm at jointing stage, 60~100cm at heading stage, and 80~100cm at filling stage of wheat were more favorable to improve the water use efficiency. It concluded that the long-term application of organic fertilizer improved the soil structure, enhanced the storage, conservation and utilization capacity of precipitation in the soil, improved the photosynthetic physiological characteristics of wheat, and promoted the increase of yield and water saving and efficiency.