不同沟垄覆盖模式下旱作马铃薯田土壤呼吸及有机碳矿化特征

Characteristics of Soil Respiration and Organic Carbon Mineralization in Dryland Potato Fields Under Different Ridge-furrow Mulching Patterns

探究不同沟垄覆盖模式下土壤呼吸速率对水热因子和有机碳矿化的响应机制,对区域碳循环发展及评估其生态效益具有重要的参考意义.于2020年在宁南山区旱作马铃薯田开展试验研究,通过设置3种沟垄比[60 cm∶30 cm(R1)、60 cm∶45 cm(R2)和60 cm∶60 cm(R3)],结合3种覆盖方式[垄上覆盖普通地膜,沟内分别覆盖秸秆(DJ)、可降解渗水地膜(DS)和不覆盖(DB)],以平作不覆盖(CK)为对照,研究不同覆盖模式下马铃薯生育期土壤水热因子、呼吸速率、有机碳含量及矿化特征.结果表明,不同沟垄比结合覆盖模式可显著提高0~60 cm层土壤蓄水量,以R3DJ处理效果较好,较CK显著提高24.99%.马铃薯全生育期3种沟垄比以R2处理增温效果最好;不同覆盖材料下DS处理具有增温效果,而DJ处理具有降温效果.不同沟垄覆盖模式均可显著提高生育期平均土壤呼吸速率,不同沟垄覆盖模式以R3DS处理最为显著,较CK处理显著提高24.71%.收获期0~20 cm和20~40 cm层土壤有机碳含量分别以R2和R1沟垄比较高,不同覆盖材料分别以DB和DS处理较高;土壤有机碳矿化速率在培养前期快速下降,中后期缓慢下降并趋于平缓,3种沟垄比下均以R3处理最高,不同覆盖材料以DS处理最高.通过生育期土壤呼吸速率与土壤水热因子的拟合方程发现,土壤水热双因子协同影响土壤呼吸的作用高于土壤水热单因子,且二次方程的水热双因子可以解释土壤呼吸的86.4%~99.9%.相关性分析表明,马铃薯全生育期平均土壤呼吸速率与0~25 cm层平均土壤温度和0~40 cm层平均土壤有机碳矿化速率呈极显著正相关,土壤温度与有机碳矿化速率呈极显著正相关.可见,沟垄比结合覆盖模式能够改善土壤水热环境,提高有机碳矿化速率,从而影响土壤呼吸速率,以沟垄比60 cm∶45 cm或60 cm∶60 cm下垄覆地膜沟覆可降解渗水地膜模式效果最好.

Exploring the response mechanism of soil respiration rate to hydrothermal factors and organic carbon mineralization under different ridge-furrow mulching modes is of high importance for the development of the regional carbon cycle and assessment of its ecological benefits.An experimental study was carried out in 2020 in a dry-crop potato field in the mountainous area of southern Ningxia by setting three furrow-ridge ratios[60 cm∶30 cm(R1),60 cm∶45 cm(R2),and 60 cm∶60 cm(R3)]combined with three mulching modes[ridge covered with ordinary plastic film,furrow covered with straw(DJ),degradable water-permeable plastic film(DS),and no mulching(DB)in furrows,respectively].The soil hydrothermal factors,respiration rate,organic carbon content,and mineralization characteristics of potatoes during the reproductive period under different mulching modes were investigated with plain mulching without mulching(CK)as the control.The results showed that different furrow-ridge ratios combined with the mulching mode could significantly increase the soil water storage capacity in the 0-60 cm layer,and the R3DJ treatment had a better effect,with a significant increase of 24.99%compared with that in CK.The R2 treatment had the best effect of increasing temperature during the whole life cycle of the potato.The DS treatment had the effect of increasing temperature,and the DJ treatment had the effect of decreasing temperature under different mulching materials.Different furrow and ridge cover patterns could significantly increase the average soil respiration rate during the reproductive period,and the R3DS treatment was the most significant among the different furrow and ridge cover patterns,with a significant increase of 24.71%compared with that in the CK treatment.The soil organic carbon content in the 0-20 cm and 20-40 cm layers at harvest time was higher in the R2 and R1 ridges,respectively,and higher in the DB and DS treatments for different mulching materials.The soil organic carbon mineralization rate declined rapidly in the early stage of cultivation and then slowly declined and leveled off in the middle and late stages,which was highest in the R3 treatment for the three types of ridge ratios and highest in the DS treatment for different mulching materials.The fitting equations of soil respiration rate with soil hydrothermal factors during the reproductive period revealed that the synergistic effect of soil hydrothermal dual factors on soil respiration was higher than that of a soil hydrothermal single factor and that the quadratic hydrothermal dual factors could well explain 86.4%to 99.9%of the soil respiration.Correlation analysis showed that the average soil respiration rate during the whole life span of the potato was highly significantly and positively correlated with the average soil temperature in the 0-25 cm layer and the average soil organic carbon mineralization rate in the 0-40 cm layer,and the soil temperature was highly significantly and positively correlated with the organic carbon mineralization rate.The furrow-ridge ratio combined with the mulching mode was shown to improve the soil hydrothermal environment and increase the rate of organic carbon mineralization,thus affecting the soil respiration rate,with a furrow-ridge ratio of 60 cm∶45 cm or 60 cm∶60 cm under the ridge mulching mulch ditch covering biodegradable seepage mulch mode being more effective.