保护性耕作下大豆农田土壤呼吸及影响因素分析

为了探讨保护性耕作对旱作农田土壤呼吸的影响,采用LI6400-09仪器(LI6400便携式光合作用系统连接6400-09呼吸室)在重庆北碚西南大学试验农场对平作(T)、垄作(R)、平作+覆盖(TS)、垄作+覆盖(RS)、平作+覆盖+秸秆速腐剂(TSD)、垄作+覆盖+秸秆速腐剂(RSD)6种处理下的西南紫色土丘陵区小麦/玉米/大豆套作体系中大豆生长季节的土壤呼吸及其水、热、生物因子进行测定和分析,探讨西南丘陵区保护性耕作下大豆农田土壤呼吸及其影响因素。结果表明,大豆整个生育期内土壤呼吸先缓慢增强,到开花期开始增长迅速,成熟期明显下降。不同处理土壤呼吸速率存在差异,表现为TTSD>TS、R>RSD>RS,土壤呼吸的土温敏感指标Q10值排序为TS>TSD>RS=R>T>RSD。秸秆覆盖处理的土壤呼吸对于土壤温度敏感性较高,垄作则降低了土壤温度敏感性。5 cm土层的土壤含水量高低排序为TSD>RSD>TS>RS>T>R。本研究中土壤呼吸与土壤水分呈抛物线函数关系,垄作处理下土壤呼吸与土壤水分正相关,达到显著水平;其他处理均表现负相关,其中TS达到极显著水平。在大豆农田生态系统中优势类群有弹尾目、螨目和双翅目,干漏斗法、陷阱法捕获的土壤动物与土壤呼吸均没有显著的相关关系,两种方法所得土壤动物数量加总与土壤呼吸进行相关分析,发现处理T相关系数达到显著水平,r=0.901,P=0.037。

Analysis of soil respiration and the influencing factors in soybean fields under conservation tillage

The effects of conservation tillage on soil respiration in dry croplands were investigated in the southwest purple hilly region. The LI6400-09 respiratory chamber was used in the experiment conducted in the experimental field of Southwest University, Beibei, Chongqing. The respiration, hydrothermal and biotic factors of soil were measured and analyzed during soybean growth period in a wheat-maize-soybean triple intercropping system. There were six treatments and each treatment replicated three times. The treatments included traditional tillage (T), ridge tillage (R), traditional tillage + straw mulching (TS), ridge tillage + straw mulching (RS), traditional tillage + straw mulching + decomposing inoculants (TSD) and ridge tillage + straw mulching + decomposing inoculants (RSD). The results suggested that soil respiration rate initially increased slowly after planting. It then increased rapidly at blossoming stage and decreased steadily at maturity of soybean. Differences were noted in soil respiration rate among different treatments and soil respiration order was T < R < TS < RS < TSD < RSD. Ridge tillage and straw mulching improved soil respiration in soybean fields. Soil temperature in 10 cm soil layer was in the order of T > TSD > TS and R > RSD > RS. Q₁₀ value, a sensitive indicator of soil respiration to temperature, was in the order of TS > TSD > RS = R > T > RSD. Q₁₀ increased under straw mulching, but the opposite occurred under ridge tillage. Soil moisture order in 5 cm soil layer was TSD > RSD > TS > RS > T > R. Soil respiration and soil moisture had parabolic function relationship, with significant correlation coefficient under R treatment. Other treatments showed negative correlations, with an extreme significant level under TS treatment. The dominant groups of soil animals in soybean fields included Collembola, Acarina and Diptera. There was no significant correlation between soil respiration and soil animals captured by tullgren apparatus and pitfall traps method. When the soil animals numbers captured by two methods were added together, the correlation coefficient under T was significant (R = 0.901 at P = 0.037).