耕作措施对缓坡耕地土壤养分分布及肥料利用率的影响

Effects of tillage measures on soil nutrients distribution and fertilizer use efficiency on gentle slope farmland

为研究不同耕作措施对坡耕地土壤养分坡面分布特征及作物产量与肥料利用率的影响,该研究在2017—2018年期间,以宁南山区10°缓坡耕地为研究对象,开展传统平作(CK)、垄沟种植(NH)、垄沟+秸秆覆盖(SM)和垄沟+地膜覆盖(PM)4种不同耕作措施对坡耕地耕层养分、作物产量的影响及其坡位效应分析研究,探讨不同耕作措施下作物肥料利用率。结果表明,相较于CK,NH、SM和PM 3种耕作措施显著提高耕层土壤有机质和土壤速效氮含量,分别提高了18.50%和14.47%、18.22%和17.64%、21.75%和18.71%,3种耕作措施之间差异并不显著。CK处理下耕层土壤有机质含量和速效氮随着坡位自上而下的变化而增加,表现出流失风险,而PM、SM和NH 3种措施表现出能够削弱坡位效应的作用,由高到低顺序为坡中、坡下、坡上。相对于CK,其他3种耕作措施下坡耕地土壤有效磷、速效钾有所降低,其中PM措施下土壤有效磷显著低于其他耕作处理。NH、SM和PM显著增加作物产量,玉米和马铃薯产量比CK分别增加27.03%和2.89%、12.85%和8.50%、204.56%和2.52%,且具有显著的坡位效应。2个覆盖措施SM和PM显著提高作物肥料利用率,种植玉米N、P利用率分别提高7.92%和16.83%、217.03%和241.59%,种植马铃薯分别提高89.43%和44.62%、97.31%和49.66%。由此可知,以垄沟、覆盖为核心的保护性耕作措施能够有效阻断养分损失途径,阻控土壤养分的坡面运移,提高肥料利用率和作物产量。

The research was carried out on 10°slope land of southern Ningxia during 2017-2018,and four different tillage measures,including conventional tillage(CK),furrow-ridge tillage(NH),furrow-ridge+straw mulching(SM)and furrow-ridge+plastic mulching(PM)were employed.The results showed that NH、SM and PM significantly increased the content of soil organic matter and available nitrogen compared with CK,increasing by 18.50%and 14.47%,18.22%and 17.64%,21.75%and 18.71%,respectively,however,there was no significant difference between the three tillage measures.The topsoil organic matter and available nitrogen of CK treatment increased from up slope to down slope showing the risk of losing from slope land.Whereas,NH,SM and PM exhibited the function of weakening the slope location effect,with the order of organic matter and available nitrogen from high to low:mid slope>down slope>up slope.Compared with CK,the soil available phosphorus and available potassium on slope land was decreased,where the soil available phosphorus under PM significantly was lower than others.The soil available phosphorus and available potassium showed low losing risk from slope land.The difference between tillages is mainly related to fertilizer input and crop absorption and utilization.NH,SM and PM significantly increased the crop yields,and the yield of maize and potato were increased by 27.03%and 2.89%,12.85%and 9.29%,204.56%and 21.52%,respectively,showing significant slope location effect.From the perspective of slope distribution,as the slope position changes from up slope to down slope,corn yields gradually increased under NH,SM and PM.Potato yields of CK increased gradually with the slope position changes from up slope to down slope;Its NH and PM increased firstly and then decreased,with the highest yield on mid slope and the lowest on down slope;Its SM decreased firstly and then increased,with the highest yield on down slope and the lowest on mid slope.Two mulching tillage methods,SM and PM,significantly improved crop N,P fertilizer use efficiency,and in the first maize planting season they were increased by 7.92%and 16.83%,217.03%and 241.59%,respectively,while in the second potato-planting season,they were increased by 89.43%and 44.62%,97.31%and 49.66%,respectively.The variance analysis was performed on the soil nutrients and crop yields at different slope positions under different tillages in 2017 and 2018.From the perspective of soil organic matter and crop yield analysis,tillages and slope positions both showed extremely significant differences between 2017(P<0.01)and significant differences in 2018(P<0.05).From the perspective of available nitrogen analysis,tillages showed significant differences(F=1.88,P<0.05)in 2017 and extremely significant differences(F=117.71,P<0.01)in 2018,slope positions both showed extremely significant differences in 2017 and 2018(F=3.43 and F=19.60,P<0.01).From the perspective of available phosphorus analysis,tillages showed significant differences(F=1.35,P<0.05)in 2017 and no significant difference(F=0.5,P>0.05)in 2018,slope positions showed extremely significant differences(F=6.74,P<0.01)in 2017 and significant differences(F=3.91,P<0.05)in 2018.From the perspective of available potassium analysis,tillages showed no significant difference(F=21.63,P>0.05)in 2017 and extremely significant differences(F=5.72,P<0.01)in 2018,slope positions showed significant differences(F=10.89,P<0.05)in 2017 and no significant differences(F=1.18,P>0.05)in 2018.Hence,it was believed that protective tillages focused on furrows and mulches can effectively block the nutrients lose,combat soil nutrients migration on slop farmland,and increase crop yield and fertilizer use efficiency.