摘要：
Slope soil is an important soil resources in the subtropical region of China where there is a relatively serious soil ero-sion caused by unreasonable utilization and heavy rainfall. Nitrogen and phosphorus losses in runoff, nutrient accumulation in southern purple slope soil (slope=15°) were monitored in field. Three treatments were set up, including longitudinal ridge (CK), cross ridge (KF) and cross ridge with straw mulching (BMP). The results indicated that runoff amount and nitrogen and phosphorus losses in runoff of the three treatments in May were very high, which accounted for more than 40% of the loss of the whole year. The mean and maximum values of nitrogen and phosphorous concentration over the whole year were all de-creased in KF and BMP treatments compared to the CK treatment. In tobacco growing season, nitrogen concentration in runoff of CK, KF and BMP were 3.44, 3.37 and 3.28 mg·L-1, respectively; in sweet potato growing season, their values were 2.79, 2.61 and 2.63 mg·L-1; in fallow season, their values were 3.01, 2.78 and 2.64 mg·L-1. The runoff losses of CK, KF and BMP were 5 553, 5 347 and 2 905 m3·hm-2, respectively, and the difference between CK and BMP was sig-nificant. The differences of runoff, total nitrogen (TN), NO-3-N, NH+4-N, total phosphorous (TP) and total dissolved phosphorous (TDP) losses in runoff between CK and BMP treatments were all significant (P<0.05), but the these differ-ences between KF and CK were not significant although the values were all decreased. At the mean time, BMP treatment in-creased the minimum precipitation value when the runoff could occur. The results indicated that the effect of cross ridge meas-ure on nutrients loss derived from runoff was limited, while cross ridge with straw mulching significantly decreased runoff and nutrients loss in steep hillslope soil.%采用田间小区试验方法,在自然降雨条件下,原位监测了南方紫色土陡坡地 (坡度=15°) 不同保护性耕作措施对地表径流量、径流水氮磷浓度及养分累积量的影响.结果表明,不同处理径流量及氮磷流失量最大的月份为5月,占全年流失量的40%以上;横坡垄作及横坡垄作+秸秆覆盖均能够降低不同作物生长季及休闲季径流水中的氮磷浓度的均值及最大值.烟草季,常规处理 (CK)、横坡垄作 (KF) 和横坡垄作+秸秆覆盖 (BMP)径流水中的总氮浓度分别为3.44、3.37和3.28 mg·L-1;甘薯季,CK、KF和BMP 3个处理径流水中总氮的浓度分别为2.79、2.61和2.63 mg·L-1;休闲季分别为3.01、2.78和2.64 mg·L-1.KF和BMP优化处理后,全年的径流量从CK处理的5553 m3·hm-2分别降至5347 m3·hm-2(KF) 和2905 m3·hm-2(BMP),其中BMP处理与CK处理之间的差异达到显著水平 (P<0.05).与CK处理相比,KF处理径流水中不同形态氮磷的流失量虽都有降低,但二者之间差异未达到显著水平,BMP处理则显著降低了径流水中总氮 (TN)、硝态氮 (NO-3-N)、铵态氮 (NH+4-N)、总磷 (TP)、可溶性总磷 (TDP) 的流失量 (P<0.05).此外,横坡垄作+秸秆覆盖还可以将起始产生径流的最小降雨量从CK处理的26.95 mm提高至67.15 mm.综上结果可以看出,单纯的横坡垄作对陡坡地的养分流失截留效果是有限的,而横坡垄作+秸秆覆盖处理则可以显著减少陡坡地的径流,进而对氮、磷养分的流失产生较好的截留效果.
