坡耕地土壤转化酶活性与芸豆产量对等高反坡阶措施的响应

Responses of soil conversion enzyme activities and kidney bean yield to contour reverse-slope terrace treatment in sloping farmland

为探究坡面微地形改造水土保持措施—等高反坡阶(CRT)对坡耕地土壤肥力的提升效果及其生态修复功能,有必要关注该措施对土壤养分与转化酶活的影响,及其提升作物产量的机制。通过分析坡耕地CRT处理后阶上和阶下0~5 cm土层养分(全氮TN、全磷TP、铵态氮NH_(4)^(+)-N、硝态氮NO_(3)^(-)-N和速效磷AP)及酶活(脲酶S-UE、β-1,4-N-乙酰葡萄糖苷酶S-NAG、亮氨酸氨基肽酶S-LAP和酸性磷酸酶S-ACP)差异,并以原状坡耕地(CK)相应位置作对照,探讨CRT措施下土壤养分转化相关酶对芸豆(Phaseolus vulgaris)产量和千粒质量的影响机制。结果表明:1)CRT使土壤TN、NO_(3)^(-)-N、TP、AP含量较CK阶上分别提高21.2%、86.2%、14.1%和28.4%,阶下提高7.3%、77.4%、21.8%和30.1%;使NH_(4)^(+)-N阶下提高2.8%,阶上降低22.5%。CRT对NO_(3)^(-)-N的提升效果高于TN和NH_(4)^(+)-N,对AP的提升效果优于TP。2)CRT措施使坡耕地S-UE、S-NAG、S-LAP和S-ACP活性阶上较CK分别提高13.4%、55.9%、56.8%和44.6%,阶下提高48.3%、72.3%、70.9%和34.6%,且阶下增幅大于阶上。3)CK坡耕地阶上、阶下芸豆产量为20.0和23.2 kg/hm^(2),千粒质量为448和376 g,而CRT使芸豆产量和千粒质量阶上提高66.7%和8.6%,阶下提高289%和26.6%,阶下增幅均大于阶上。4)相比CK,CRT使坡耕地芸豆产量与S-UE由不相关变为显著正相关(P<0.05),相关系数由0.12增至0.91,使坡耕地芸豆千粒质量与氮、磷、酶活(S-NAG、S-LAP、S-ACP)由显著负相关(P<0.05)变为相关。S-LAP、S-NAG、NH_(4)^(+)-N对芸豆产量和千粒质量的影响显著(P<0.01),解释量分别为48.4%、29.2%、18.0%。CRT通过改善坡耕地土壤养分的空间分布,提高相关酶活,加速有机养分向无机养分的转化,提升土壤关键性肥力,进而促进芸豆生长发育,提高产量和千粒质量。

[Background]In order to explore the improvement effect of slope microtopographic modification soil and water conservation measure-contour reverse-slope terrace(CRT)on soil fertility and its ecological restoration function in sloping farmland,it is necessary to pay attention to the effect of CRT on soil nutrients and enzyme activities related to nutrient conversion,as well as its contribution and mechanism to crop yield.[Methods]Soil nutrients(TN,TP,NH_(4)^(+)-N,NO_(3)^(-)-N and AP)and soil urease(S-UE),soilβ-1,4-N-acetylglucosidase(S-NAG),soil leucine aminopeptidase(S-LAP)and acid phosphatase(S-ACP)were analyzed in the sloping farmland 0-5 cm soil of two terrace positions(aboveandbelow the terrace)under CRT treatments,and the corresponding position of the unaltered sloping farmland(CK)was taken as the control.The effects and mechanism of soil nutrient conversion related enzymes on yield and 1000-grain weight(TGW)of kidney bean(Phaseolus vulgaris)under CRT were investigated.[Results]1)Compared to CK,the contents of soil TN,NO_(3)^(-)-N,TP and AP in CRT increased by 21.2%,86.2%,14.1%and 28.4%in the slope above the terrace,but 7.3%,77.4%,21.8%and 30.1%in the slope below the terrace.The NH_(4)^(+)-N increased by 2.8%in the slope above the terrace and decreased by 22.5%below the terrace in CRT.The enhancement effect on NO_(3)^(-)-N was higher than that on TN and NH_(4)^(+)-N,and the enhancement effect on AP was better than that on TP.2)Compared to CK,the S-UE,S-NAG,S-LAP and S-ACP activities increased by 13.4%,55.9%,56.8%and 44.6%in above the terrace of CRT,and 48.3%,72.3%,70.9%and 34.6%in below the terrace of CRT.Moreover,the increase rate of below the terrace was greater than that of above the terrace.3)The per hectare yield of kidney bean were 20.0 and 23.2 kg/hm^(2),and TGW were 448 and 376 g in CK sloping farmland(above and below the terrace),while yield increased by 66.7%and 289%(above and below the terrace),TGW increased by 8.6%and 26.6%(above and below the terrace)under CRT treatment.And the increase rate of below the terrace was greater than that of above the terrace.4)Compared with CK,CRT changed kidney bean yield and S-UE from non-correlation to significant positive correlation(P<0.05),the correlation coefficient(R)increased from 0.12 to 0.91,and the TGW of kidney beans in slopingfarmland land changed from negative correlation(P<0.05)to correlation with nitrogen,phosphorus nutrients and enzymes(S-NAG,S-LAP and S-ACP).S-LAP,S-NAG and NH_(4)^(+)-N had significant effects on yield and TGW of kidney bean(P<0.01),explains rate were 48.4%,29.2%and 18.0%,respectively.[Conclusions]CRT accelerates the conversion of organic nutrient to inorganic nutrient,promotes the growth and development of kidney bean,and increases the yield and TGW by improving the spatial distribution of soil nutrients,which increases the activities of related enzymes in sloping farmland.