不同灌溉方式下3种土壤微生物活性测定方法比较

Comparison of three methods used to determine soil microbial activity under different irrigation systems

探究不同灌溉方式下土壤微生物活性,对维持土壤稳定和提高水资源利用效率具有重要意义。以沈阳农业大学长期定位灌溉试验基地为平台,采用土壤酶活性、土壤呼吸和微量热法,研究节水灌溉组覆膜滴灌、渗灌及对照组沟灌下的土壤微生物活性并比较3种微生物活性测定方法。结果表明:不同灌溉方式下土壤脲酶、转化酶、脱氢酶活性无显著差异,土壤呼吸在3个主要生长季也没有明显变化规律;而微量热法得到的热功率时间曲线呈现了典型的微生物生长特征趋势,覆膜滴灌的生长速率较大,且与沟灌的总热量、最大热功率相差不大。因此,从可持续农业观点出发,覆膜滴灌是保证土壤微生物活性较高的一种节水灌溉方式;微量热法也为传统方法下不易检测的微生物活性提供了新思路。

Irrigation is a main agricultural management measure in arid regions. The area of irrigated farmland has reached 58.5 million hectares in China, and the area of water-saving irrigation has reached 29.0 million hectares with the development of sustainable agriculture. However, furrow irrigation is still widely used, especially in vegetable fields, which require multiple water sources. This results in the waste of water and issues relating to soil quality. Recent studies have demonstrated that irrigation can change the soil moisture conditions, and thus affect soil microbial activity. Soil microbial activity, a significant assessment index for soil quality, links the microbial community structure with ecosystem function. Therefore, determining microbial activity, both accurately and quickly, is important for the evaluation of soil microbial metabolism. Several approaches have been utilized to analyze soil microorganism activity in many studies. Soil enzyme activity and soil respiration are widely used; however, the results might lack accuracy due to certain limitations. Therefore, the objective of this study was to analyze the effects of different irrigation methods on soil microbial activity, which was assessed by soil enzyme activity, soil respiration, and microcalorimetric methods, based on a long-term irrigation experiment in Shenyang Agriculture University. Three irrigation methods were investigated, including drip irrigation （ D）, subsurface drip irrigation （S）, and furrow irrigation （F） as a control. The results showed there was no significant difference in soil enzyme activity or soil respiration under different irrigation systems. Compared with conventional methods, the microcalorimetric method provided more useful information on changes in the soil microbial activity. The microcalorimetric method produced a power-time curve, which was a typical microbial growth curve. Based on the soil thermal dynamic index, changes in total heat, maximum thermal power, and growth rate under drip irrigation and furrow irrigation were negligible. No difference in microbial activity was observed between drip irrigation and furrow irrigation; however, activity was the lowest with subsurface drip irrigation. Therefore, drip irrigation with plastic was the method of water-saving irrigation most suitable for maintaining higher microbial activity in sustainable agriculture. Thus, the technology of subsurface drip irrigation should be further improved. Furthermore, the microcalorimetric method represents a novel way of detecting microbial activity, which was difficult to detect using traditional methods. As a consequence, the use of traditional methods to determinate soil microbial activity is limited, and the microcalorimetric method is highly sensitive for the determination of soil microorganism activity.