| Soil and water conservation(SWC)practices have been long-time recognized as a tackle to soil erosion,and maintain sustainable agriculture on sloping farmland.Non-point source pollution has become one of the key concerns in the polluted environment of river basins in China.However,most of the studies focused on the individual character of soil erosion or nutrient losses in short slope plots.This study expected to investigate soil and nutrient loss by eroded sediment and runoff flux,and an effect of these practices to crop yield in the long slope plots.A total of 12 plots were included in this study that was assigned to four treatments(20m x 4m,gradient 15°):Control(C),contour farming(CF),Contour farming with mulch(CM),and Contour farming with hedgerow(CH).The runoff volume and sediment yield,their concentration,rainfall were monitored by a period of the rainy season in 2019.During the experimental test,25 rainfall ranged from 0.4 to 85.82 mm with fell 255.02 mm of precipitation.The main factor in soil erosion and nutrient losses are directly related to precipitation and its consequences.Correlation analysis shows that for all treatments,there were highly significant and positive correlation between rainfall and runoff(r2=0.95-0.97,P<0.01),and between rainfall and soil loss(r2=0.98-0.99,P<0.01)The seasonal average runoff loss ranged between 63.42 and 472.06 m3/ha,with an average was 272.32 m3/ha.The results exposed that the amount of nutrient and sediment loss in the runoff plots,compared to the control treatment was much lower.The result of contrast tests in ANOVA(t=24.70 d.f.=8,P<0.05)indicated that runoff losses in the CH and CM fields were performed excellently to preventing runoff loss,followed by CF treatment,compared with the C treatment.In contrast,the sum of runoff loss in each treatment decreased by a minimum of 17.05%,86.56%,and 65.62%,respectively.The seasonal soil loss range of C was 369.79-3668.02 kg/ha,with an average 1724.98 kg/ha.The C treatment soil loss was high,ANOVA indicated that(F=1286.88,d.f.=3,P<0.05)there is a significant difference with all treatments.Experimental results show that soil erosion is reduced from 37.93-89.91%compared to the C treatments.The TN losses ranged from 2808.8 to 7003.07 g/ha in the experimental area.Compared with that of the C treatment,the TN losses in the CF,CM,and CH treatments decreased by 19.67,59.89,and 56.75%,respectively.The TN losses due to eroded sediments accounted for the majority of the total TN loss in all experimental treatments,while the TP losses ranged from 1968.83 to 4380 g/ha,with 8.7 to 43.85%of the TP lost by runoff.The amount of nutrient loss in the soil is directly associated with the sum of eroded sediment and volume of runoff and its concentration.Soil nutrient loss decreased,with a minimum nitrate-nitrogen of 1.81%for CF treatment,and with a maximum NN of 98.12%for CM treatment compared to the C treatment in the experimental plots.The total crop yields for treatments were ranged between 742.11 and 1257.89 kg/ha,with average crop yields was 1056.80 kg/ha.Compared with the C treatment,CH treatment was the highest yielding experiment.However,runoff volume and the amount of sediment loss in the CM treatment were significantly deducted than other treatments,but crop yield also decreased by 22.35%.Although it is concluded that these conservation practices could reduce runoff and nutrient loss on a sloping farm.This experiment was done to the limited time of investigating,the SWC effect of straw mulching and Vetiver planted during the year may be underestimated,and more extensive observation experiments are needed.In particular,the analysis of the combined effects of fertilization measures and Vetiver measures on soil-water and nutrient loss in the study field is still lacking,and the consequences of simultaneous use of both measures need to be studied in subsequent experiments. |
PDF Full Text Request