阴山北麓不同轮作模式对土壤理化性质及呼吸的影响

Influence of Different Crop Rotation Patterns on Soil Properties and Soil Respiration in Rainfed Field

不同作物对土壤碳汇及土壤理化性质的影响不同，不同轮作模式对土壤碳汇能力的影响也不同。笔者设计连续5年6种轮作模式试验，探究轮作模式影响土壤理化性质、土壤呼吸、微生物量碳的机理。结果表明，在越冬后，由于该地区多风、干旱和少雨等气候环境，土壤蒸发导致20cm以上土层水分丧失严重，含水量呈随土层深度加深而增加的趋势。S2和S3能显著提高土壤越冬保水能力，在秋收后大部分处理的土壤含水量能达到14％，在越冬后还能保持在8％～10％的水平上，而其他处理均降到5％以下；同时，S2和S3能保持土层的不同深度的含水量都在较高水平，均匀稳定，其他处理随土层加深水分流失严重。土壤地表温度最高峰出现在8月上旬，S7，S3的地表温度（约25℃）显著低于其他处理（30～35℃），而在50cm深层土壤又高于其他处理，该处理温度的稳定性不仅表现在土层深度之间，同时表现在全生育期，不随夏季气候变化而发生剧烈的起伏。土壤呼吸值（土壤微生物，植物根呼吸）在全年总体水平上S9〈S2〈S3〈S4〈S8〈S10〈S1〈S5〈S6〈S7，轮作处理能明显降低表层土有机碳矿化的散失，保持土壤碳汇能力。研究还发现土壤呼吸和土壤地表温度呈显著相关。燕麦苜蓿混作（1年）、苜蓿（1年）、燕麦（1年）、马铃薯（2年）和燕麦苜蓿混作（1年）、苜蓿（1年）、马铃薯（3年）这2个轮作模式可以有效提高土壤碳汇能力，改良土壤理化性质。

Soil carbon sink and soil physical and chemical properties are influenced by different crops and different rotation patterns. The author designed 6 rotation patterns over 5 years, in order to study the impact of rotation on soil physical and chemical properties, soil respiration and microbial biomass carbon. The results showed that after winter, due to the windiness, drought and less rainfall condition, the loss of soil moisture above 20 cm layer was serious because of the soil evaporation, and soil moisture increased with the increase of soil layer. Treatments S2 and S3 could significantly increase the capacity of retaining soil moisture after winter; after harvest, soil moisture of most treatments could reach 14% and maintain at 8%- 10% after winter, while soil moisture of the other treatments dropped down to below 5%. At the same time, treatments S2 and S3 could keep soil moisture of different depths at a higher, uniform and stable level, the others lost moisture greatly. The soil surface temperature peak was in the early August. The surface temperatures of S3 and S7 （25℃） were significantly lower than that of the other treatments （30-35℃）, but the temperature of 53 was higher than that of the others at 50 cm soil layer. The stability of the temperature of S3 was shown between the soil depths, as well as the whole growth period, with no variation with summer climate changing. The order of year soil respiration （soil microbial and plant root） was S9〈S2〈S3〈S4〈S8〈S10〈S1〈S5〈S6〈S7, crop rotation could reduce the loss of surface soil organic carbon mineralization significantly, and maintained soil carbon sequestration capacity. The study also showed that soil respiration was significantly correlated to soil surface temperature. In conclusion, oats-alfalfa intercropping 1 year, alfalfa 1 year, oats 1 year, potato 2 years and oats-alfalfa intercropping 1 year, alfalfa 1 year, potato 3 years could effectively increase the ability of soil carbon sequestration and improve soil properties.