紫花苜蓿与多年生黑麦草不同种植模式下沙化土壤碳、氮含量和酶活性研究

Study on the contents of carbon,nitrogen and enzymes activities of sandy soil grown alfalfa and perennial ryegrass with different planting patterns

通过豫北地区连续6年定位试验,以沙化裸地为对照,研究了紫花苜蓿单播、多年生黑麦草单播、紫花苜蓿与多年生黑麦草混播3种种植模式下土壤碳、氮含量和相关土壤酶活性,并分析了其间的相互关系。结果表明:与沙化裸地相比,0~40cm土层3种种植模式下土壤碳、氮含量均不同程度地增加。其中,土壤有机碳含量表现为紫花苜蓿与多年生黑麦草混播模式下最高,为9.17g/kg;土壤全氮和碱解氮含量表现为紫花苜蓿/多年生黑麦草混播和紫花苜蓿单播模式下最高,且二者之间无显著性差异(P>0.05);紫花苜蓿/多年生黑麦草混播模式下土壤脲酶、蛋白酶、蔗糖酶、淀粉酶和纤维素酶活性最高,分别比沙化裸地增加266.80%、87.79%、49.96%、433.26%和232.38%;相关性分析表明,土壤有机碳分别与蔗糖酶和淀粉酶呈极显著(P<0.01)和显著(P<0.05)正相关,土壤碱解氮与脲酶呈显著正相关(P<0.05)。因此,试验中蔗糖酶、淀粉酶和脲酶可表征土壤碳、氮特征。由此认为,相对于沙化裸地,豫北地区经6年人工草地建植,土壤碳、氮含量以及相关土壤酶活性有效提高,以紫花苜蓿/多年生黑麦草混播为最佳的种植模式。

The effect of three planting patterns (alfalfa single-sowing,perennial ryegrass single-sowing,alfalfa and perennial ryegrass mixed-sowing) on the contents of carbon,nitrogen and enzymes activities of sandy soil was studied through 6 years' fixed test in northern Henan province.And the relationship among tested indexes was analyzed.The results showed that compared with sandy bare land,the contents of carbon and nitrogen in 0~40 cm soil layer increased at different degrees under three planting patterns.Among them,the highest value of soil organic carbon was occurred in alfalfa and perennial ryegrass mixed-sowing (9.17 g/kg).The highest values of total nitrogen and available nitrogen were appeared in alfalfa and perennial ryegrass mixed-sowing and alfalfa single-sowing,and there was no significant difference between them ( P >0.05).The highest values of soil enzymes activities were obtained in alfalfa and perennial ryegrass mixed-sowing.Compared with sandy bare land,the activities of urease,protease,sucrase,amylase and cellulase increased by 266.80%,87.79%,49.96%,433.26% and 232.38%,respectively.Correlation analysis showed that soil organic carbon was positively correlated with sucrase ( P <0.01) and amylase ( P <0.05),and soil available nitrogen was positively correlated with urease ( P <0.05).The contents of carbon,nitrogen and related enzymes activities were effectively increased after six years of forage growing,and alfalfa and perennial ryegrass mixed-sowing was the best.