甘蔗等高种植与新植配置比例对坡面沟蚀引起的氮磷养分流失的影响

Effects of Configuration Ratios for Contour Planting and Replanted Sugarcane on Gully Erosion-Induced Nitrogen and Phosphorus Losses on Slopes

[目的]探讨甘蔗等高种植与新植适宜的配置比例,为甘蔗种植区减少坡面沟蚀和养分流失、提升耕地质量和合理种植甘蔗提供技术支撑。[方法]通过野外测量与试验分析相结合,确定苗期、分蘖期、伸长期和成熟期4个甘蔗生长时期内低、中、高3种等高种植和新植比例的甘蔗坡面沟蚀量和养分流失量,并明确其影响因素。[结果](1)整个甘蔗生育期,那辣流域甘蔗种植坡面沟蚀及其导致的全氮、全磷流失量分别在31.3~66.3 t/hm^(2),39.0~82.5 kg/hm^(2),18.0~38.4 kg/hm^(2)之间;(2)苗期是那辣流域沟蚀和养分流失的主要时期,其贡献量占甘蔗全生育期的比例为47.7%~57.7%。(3)全生育期,高比例等高(H_C)的坡面沟蚀和养分流失比低比例新植坡面(L_C)低33.03%~35.42%(p<0.05),但中比例等高(M_C)和H_C,L_C的流失量均不显著;低比例新植(L_(Rp))坡面沟蚀和养分流失量比高比例新植(H_(Rp))低27.41%~32.98%,比中比例新植(M_(Rp))低21.02%~25.86%(p<0.05),凋落物覆盖度和根系密度是影响沟蚀与养分流失的重要因素。(4)全生育期,坡面全氮和全磷流失量分别占年氮肥和磷肥施用量的24.1%~39.5%和107.0%~156.7%。[结论]在甘蔗种植时,60%以上的等高种植比例和30%以下新植比例,可以有效减少坡面土肥流失。

[Objective]The suitable configuration ratios for contour planting and replanted sugarcane on slopes were determined in order to provide technical support for reducing slope ditch erosion and nutrient loss,improving cultivated land quality and rational sugarcane planting in sugarcane planting area.[Methods]Three configuration ratios(high,medium,and low)for contour planting and replanted sugarcane were evaluated.Slope-gully erosion and nutrient losses were determined by field measurements and laboratory experiments at the growth stages of establishment growth(EG),vegetative growth(VG),grand growth(GG),and ripening growth(RG),and the factors influencing erosion and nutrient loss were determined.[Results]①During the total growth(TG)of sugarcane,the total nitrogen(TN)and total phosphorus(TP)losses caused by gully erosion on slopes planted to sugarcane in the Nala River basin were 31.3—66.3 t/hm^(2),39.0—82.5 kg/hm^(2) and 18.0—38.4 kg/hm^(2),respectively.②EG was the main stage of gully erosion and nutrient losses in the Nala River basin,accounting for 47.7%—57.7%of the total erosion and nutrient losses.③During TG,gully erosion and associated nutrient losses for higher contour ratios(H C)were 33.03%—35.42%lower than for lower contour ratios(L C)(p<0.05),but the losses for medium contour ratios(M C)were not significant compared with those of H C and L C.Gully erosion and nutrient losses of lower replanted ratios(L Rp)were 27.41%—32.98%lower than those of higher replanted ratios(H Rp),and 21.02%25.86%lower than those of medium replanted ratios(M Rp)(p<0.05).Litter cover and root density were the important factors affecting gully erosion and nutrient losses.④During TG,TN and TP losses on slopes accounted for 24.1%—39.5%and 10^(7).0%—156.7%of the annual N and P application,respectively.[Conclusion]Planting sugarcane on slopes with a contour planting ratio of greater than 60%and a replanted ratio of less than 30%can effectively reduce soil and nutrient losses on slopes.