适宜的水氮处理提高稻基农田土壤酶活性和土壤微生物量碳氮

为探讨节水灌溉与氮肥施用对稻田土壤微生物特性的影响，该试验采用防雨棚池栽试验，研究2个灌溉模式（常规灌溉与控制灌溉）与3个水平施氮量（90、180和270 kg/hm2））对稻基农田土壤脲酶活性、土壤过氧化氢酶活性、土壤磷酸酶活性、土壤转化酶活性、土壤微生物量碳及土壤微生物量氮的影响。研究结果表明，随着施氮水平增加，土壤脲酶活性和土壤微生物量氮增加，土壤过氧化氢酶活性、土壤磷酸酶活性、土壤转化酶活性、土壤微生物量碳、土壤微生物量碳与土壤微生物量氮的比值、土壤微生物熵均呈先增加后降低趋势；与常规灌溉相比，控制灌溉显著提高稻基农田土壤脲酶活性、土壤过氧化氢酶活性、土壤磷酸酶活性、土壤转化酶活性、土壤中微生物量碳、土壤微生物量氮、土壤微生物熵，降低土壤微生物量碳与土壤微生物量氮的比值。在该试验条件下，以控制灌溉模式下施氮量180 kg/hm2可获得最优的生物环境，土壤脲酶活性、土壤过氧化氢酶活性、土壤磷酸酶活性、土壤转化酶活性、土壤中微生物量碳、土壤微生物量氮分别达到3.02×10-2 mg/g、0.93 mL/g、5.70 mg/g、10.08 mL/g、237.58 mg/kg、52.60 m/kg。该研究对认识稻基农田水氮耦合关系、指导江淮丘陵季节性干旱区水稻优质节水高产高效栽培实践提供理论依据。

Suitable water and nitrogen treatment improves soil microbial biomass carbon and nitrogen and enzyme activities of paddy field

Abstract: The soil microbial biomass, enzyme activities and microbial community structure have always been at the core of soil ecosystems, because they are the indicators for soil fertility thus play significant role in sustainability of cropping systems. As a result, much research has focused on the impact of different soil types, management measures and cropping systems on soil microbial biomass and enzymatic activities. However, few reports have focused on effect of water and nitrogen on soil microbial biomass carbon and nitrogen and enzyme activities of paddy field. Distribution of precipitation is inconsistent and asynchronous with evaporation, creating conditions for severe summer and autumn droughts in the hilly region of southern China. Jianghuai hilly region is a part of hilly region of southern China, where seasonal drought regions are widely distributed. High temperatures have caused severe drought during the past 60 years. Seasonal drought often seriously affects rice production due to water stress. As a result, it is necessary to set up new water-saving and fertilizer-saving rice cultivation systems to increase water use efficiency and fertilizer use efficiency thus reduce yield loss caused by drought. This study was designed to investigate the effects of irrigation and nitrogen (N) fertilization on soil microbial biomass carbon and nitrogen and enzyme activities of paddy field. The experiments were conducted in pools within rain-proof shelter at the Agricultural Science Research Institute of Anhui Science and Technology University in Fucheng Town, Fengyang Country, Anhui Province. Samples were collected from treatments under control and conventional irrigation receiving N application of 90 kg/hm2, 180kg/hm2, and 270kg/hm2. Conclusion: Results showed that irrigation and nitrogen fertilization significantly influenced on soil microbial biomass carbon (SMBC), microbial biomass nitrogen (SMBN) and enzyme activities of paddy field. With the increment of N application rates, soil urease activity and SMBN increased, while soil catalase activity, phosphatase activity, and invertase activity, SMBC, SMBC/ SMBN and soil microbial quotient were highest at 180 kg/hm2 of N applied. Compared with conventional irrigation, soil urease activity, soil catalase activity, phosphatase activity, invertase activity, SMBN, SMBC and soil microbial quotient increased, and while SMBC/ SMBN decreased under control irrigation. We concluded that control irrigation combined with suitable N application rate (180 kg/hm2) could benefit for soil biological environment establishing under the experiment. This study revealed that the soil biological health could be enhanced due to the rational application of water and fertilizer. The reasonable amount of soil water and nutrition can provide the suitable environment to the soil biota, and then the soil biota can provide the essential nutrient to the rice growth and development. In the hilly region of southern China, the increasing scarcity of water resources seriously restricts agricultural development. Adopting water-saving and fertilizer-saving rice cultivation patterns can reduce irrigation water, decrease water consumption, and relieve the stress of water application. This research aids in the sustainable development and effective production of rice cultivation and optimal use of water and fertilizer during seasonal droughts hilly region of southern China.