| The slope-lands non-woody forest is the most productive forest,and rice(Oriza sativa L.)is one of the top three food crops.The problems of inappropriate management and fertilization are accounting for soil erosion,nutrient runoff losses in non-woody forest and the decrease in chemical nitrogen efficiency as well as soil nitrogen level,which need pay more attentions.In this paper,the effects of balanced fertilization,vegetation management on soil erosion,nutrient runoff loss in tea garden and bamboo forest were studied.The effects of organic manure used as partial substitute of chemical nitrogen on soil nitrogen status,rice growth and chemical nitrogen fertilizer utilization were studied.The results were as follow:1.A runoff observation experiment in tea garden was conducted from November,2016 to October,2017.The experiment included four treatments such as T1(conventional fertilization and normal management),T2(balanced recommendation fertilization and normal management),T3(conventional fertilization with Albizzia julibrissin)and T4(balanced recommendation fertilization with Albizzia julibrissin).Amounts of cumulative runoff water or sediment of T3,T4 treatments were significantly(P<0.05)lower than those of T1,T2 treatments.The total nitrogen(TN)concentrations in runoff water of T2,T4 treatments were significantly(P<0.05)lower than those of T1 treatment at all times,T3 had similar effection to T1 treatment expect May 27;June 14,September 26th,October 18.The total phosphorus(TP)concentrations in runoff water of T2,T3,T4 treatments were significantly(P<0.05)lower than those of T1 treatment after feitilization.With the comparesion to T1 treatment,the cumulative TN losses in runoff water of T2,T4 treatments decreased significantly(P<0.05),being contributed to the decrease in concentrartions of soluble ammonium nitrogen,nitrate nitrogen.With the comparesion to T1 treatment,the cumulative TP losses in runoff water of T2,T3,T4 treatments decreased significantly(P<0.05),being contributed to the decrease in concentrartions of soluble inorganic phosphorus.With the comparesion to T1 treatment,the cumulative TN losses in sediment of T4 treatment decreased significantly(P<0.05),the cumulative TP losses in sediment of T3,T4 treatments decreased significantly(P<0.05).The annual total cumulative TN or TP losses of T2,T3,T4 treatments were significantly(P<0.05)lower than those of T1 treatment.1).Compared with T1 treatment,the amount of runoff water,sediment,nitrogen and phosphorus carried by runoff water and sediment of T4 treatment were significantly reduced.Therefore balanced recommendation fertilization conbined with planting Albizzia julibrissin is an appropriate technology which could effectively control soil erosion and nutrient losses in tea garden.2.A runoff observation experiment in bamboo forest was conducted from January to December 2017.The experiment included six treatments such as T1(conventional fertilization and normal management),T2(balanced recommendation fertilization and normal management),T3(no fertilization and normal management),T4(conventional fertilization with Adinandra milletii),T5(balanced recommendation fertilization with Adinandra milletii)and T6(no fertilization with Adinandra milletii).Amounts of cumulative runoff water or sediment of planed Adinandra milletii(T4,T5,T6)treatments were significantly(P<0.05)lower than those of none Adinandra milletii(T1,T2 T3)treatments.The TN or TP concentrations in runoff water of balanced recommendation fertilization treatments(T2,T5)were significantly(P<0.05)lower than those of conventional fertilization treatments(T1,T4).The TN or TP concentrations in runoff water of treatments with Adinandra milletii(T4,T5,T6)were significantly(P<0.05)lower than those of normal management(T1,T2,T3).With the comparison to T1,T4 treatments,the cumulative TN or TP losses in runoff water of T2,T5 treatments decreased significantly(P<0.05),being contributed to the decrease in concentrartions of soluble ammonium nitrogen,nitrate nitrogen and inorganic phosphorus.T4,T5,T6 treatments had similar effect to T1,T2,T3 treatments.With the comparesion to T1,T2 treatmens,the cumulative TN or TP losses in sediment of T4,T5 treatments decreased significantly(P<0.05).Compared with T1 treatment,the amount of runoff water,sediment,nitrogen and phosphorus carried by runoff water and sediment of T5 treatment were significantly reduced.Therefore balanced recommendation fertilization conbined with planting Adinandra milletii is an appropriate technology which could effectively control soil erosion and nutrient losses in bamboo forest.3.A rice-rice cropping experiment was conducted.The experiment included six treatments such as CK(no fertilizer treatment),PK(chemical fertilizers with phosphorus and potassium treatment),FP(farmer practice treatment),M(20%N)(organic manure alone),CM(N)(integrated fertilization with normal nutrient doses treatment),CM(-N)(integrated fertilization with reduced nitrogen dose treatment).Compared with CK treatment,soil water-soluble NH4+-N and water-soluble NO3--N concentrations of CM(N)or CM(-N)treatment were significantly(P<0.05)higher at seedling establishment and maximum tillering stages of early rice.Compared with CK treatament,soil water-soluble NH4+-N and soluble organic nitrogen concentrations of CM(N)or CM(-N)treatments were significantly(P<0.05)higher at seedling establishment and maximum tillering stages of late rice.Alkali-hydrolyzable nitrogen concentrations of CM(N)and CM(-N)treatments were significantly(P<0.05)higher than those of CK treatment at all stages in early and late rice growing season.Soil water-soluble N and alkali-hydrolyzable nitrogen concentrations of CM(N)and CM(-N)treatments were similar to FP treatment.Twenty four soil samples were collected at the harvest stage of late rice in 2016.The fraction of soil organic nitrogen was analyzed.The concentrartions of ammonium nitrogen and amino sugar nitrogen in soil hydrolysable organic N of CM(N)or CM(-N)treatment was significantly(P<0.05)higher than that of FP treatment.Compared with CK treatment,soil total nitrogen and acid hydrolysable nitrogen concentrations of CM(N)or CM(-N)treatments were significantly(P<0.05)higher.Therefore,organic manure used as 20%substitute of chemical nitrogen can effectively improve soil nitrogen status.4.A rice-rice cropping experiment was conducted.The treatment design was the same as the former experiment with rice-rice rotation.The results showed that concentrations and acumulated amounts of nitrogen,phosphorus or potassium in rice hull,unpolished rice,unfilled grain,grain,straw of CM(N)and CM(-N)treatments were significantly(P<0.05)higher,compared with CK treatment.The grain yield or total shoot biomass of early or late rice of CM(N)and CM(-N)treatments were significantly(P<0.05)higher than those of CK treatment.Apparent chemical nitrogen recovery by early or late rice of CM(N)and CM(-N)treatments were significantly(P<0.05)higher than those of FP treatment,and the grain yield of later rice,annaul rice were similar to FP treatment.Therefore,organic manure used as 20%substitute of chemical nitrogen can catch nutrient needs of rice plants;retain grain yield,improve chemical nitrogen use efficiency,which is an appropriate nitrogen fertilizer management technology for rice-rice cropping. |
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