| In recent yeast，as the increasing of population and the continuous improvement ofliving standards, social demand of vegetables is gradually increased, the vegetableproduction in protectorate has been developed rapidly in all parts of the country. A greatdeal of fertilizer, especially nitrogen fertilizer, was used by farmers in order to pursue themaximum economic benefit, which not only led to reduce the nitrogen use efficiency, butalso increased the degradation of soil quality and environment pollution. Aiming atresolving these questions, a2-years test was carried out in Xushui County, Hebei province.Therefore this paper took the greenhouse that planted spring tomatoes over11years as theresearch object, and studied the influences of reasonable optimized fertilization and plantcatch crop before plant tomatoeson the yield, the economic benefit, N use efficiency, theleaching of nitrate nitrogen and the content of nitrate nitrogen of spring tomatoes throughthe experiments in two years. By mean of the data we had analyzed the effect of the soilinorganic distribution and apparent N balance of soil-crop system during the monitoringperiod for two consecutive years of the different treatments.The main conclusions are asfollows:1) The effects of fertilization on tomato yield and economic benefit were studied andidentified. The results showed that: in two consecutive years of monitoring period,compared with no nitrogen fertilizer (CK), the tomato yield of the treatment of Onlymanure (OM)、 manure and conventional chemical fertilization(MC)、 Manure andoptimum chemical fertilization（MOC1、MOC2） and sweet corn as a catch crop allsignificantly increased. The tomato yield of optimized chemical fertilization and plantingcatch crop has increased then conventional chemical fertilizer, but the difference is notsignificant.(2) The treatment of optimum chemical fertilization can improved the N useefficiency for tomato. The tomato growing season in2011, for the higher soil fertilization,N use efficiency of four treatments (MC, MO1, MO2and MCC) at the low level, is about5%. But the N use efficiency of MO1(6.46%) is significantly higher than other treatments.After tomato harvest in2012the N use efficiency of each treatments has a different degree of increase in addition to the OM, is over5%. MO1reached7.19%, significantly higherthan the other treatment in the same year, and was higher than that in2011. The optimizedfertilization can effectively improve the N use efficiency and was more obvious along withincreasing of the planting years.3) The content of NO3--N in0-200cm soil of the treatment MC is the highest.Compared with MC, the content of NO3--N for three treatments (MO1, MO2and MCC)has decreased. In a word, the content of NO3--N in0-200cm soil between MCC andMO1is significant difference. Each layer of soil NO3--N content in MO2is lower thanMCC. Optimized fertilization and sweet corn as catch crop before plant tomato caneffectively reduce the content of NO3--N in the0-200cm soil after tomato harvest.4) The amassing heavy rainfall period is NO3--N leaching keyt stage. Collected theleaching water of underground90cm. The result showed that for a large number ofnitrogen fertilizer has input to treatment MC, the nitrate nitrogen leaching amount issignificantly higher than other treatments at open tent period, occupied in the total nitrogenfrom7.97%-8.31%. The NO3--N leaching amount of MCC is higher than other threetreatments (MO1MO2and OM) though the sweet corn has absorbed part of nitrogen atcatch season. because we has input the vast fertilizer as the treatment of MC to thistreatment at the tomato growed period. Optimize fertilization is superior to planting catchcrops in terms of reduction of nitrate nitrogen leaching.(5)The results of the apparent nitrogen balance in soil vegetable system indicated:there is a risk of nitrogen leaching after the main crop season tomato planting for thelong-term high nitrogen level into the soil. The two years of monitoring, after tomatoharvesting, each treatment had a large number of nitrogen surplus. As a performance, thenitrogen surplus increased with the increased amount of nitrogen applied into the soil.Studied the result of the2011can showed that the nitrogen surplus amount of eachnitrogen fertilizer treatments is more than1400kg.ha, and MC is significantly higher thanthe other treatments. Compared with MC, the treatments of OM, MO1, MO2and MCCwere decreased by556.21kg.ha,241.65kg.ha,311.13kg.ha, and280.56kg.ha. Accordingto the data from2012, the nitrogen surplus amount showed a trend of growth then2011.In tomato growth period for two years, the soil mineralization nitrogen and initial soilinorganic nitrogen, has been far more than the nitrogen that crop had uptake. So we shouldbe fully considered the the nitrogen supply ability of the soil oneself. Be sure to rememberon-demand fertilization. Bear in mind that blind fertilization in the actual agriculturalproduction.Planted the sweet corn as catch crop at leisure period, the results show that the sweetcorn can reduce the soil (0-200-cm) nitrate nitrogen content effectively and reduce therisk of nitrate leaching greatly. |
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