| Nitrogen fertilizers play an important role in agriculture. However, nitrogen use efficiency is reduced from many reasons such as NHs volatilization, nitrate leaching, denitrafication, and so on. The major season of nitrate leaching is the monsoon, which causes the strong intensity of rainfall when the corn (Zea mays L) is growing in fields of the Loess Plateau region. Localized compaction and ridge fertilization is a method for nitrogen fertilizer application, by which less fertilizer leaching would occur. The soil water movement and nitrate transport in soil profile, the yield of corn and nitrogen use efficiency under localized compaction, flat and ridge were investigated in two year studies of field conditions. The factors that influence nitrate transport were studied based on simulation rainfall experiment, too. In addition, the relation between nitrogen nitrification with soil bulk density was investigated through culture experiment. The results showed that:1. The movement and distribution of soil water were affected by fertilization methods through different micro-topography. Downward water movement in the fertilizer bands was minimized by the barriers of localized compaction and ridge. Water infiltrated in furrows primarily and moved to row positions laterally under ridge condition during rainfall. In the field, the effect of micro-topography on soil water movement and distribution in soil profiles showed clearly if there was lower soil water content before rainfall. And the effect of micro-topography was reduced if more rainfall occurred. Compared with flat, evaporation below the rows was minimized under ridge, thus status of soil water was improved by the ridge under dry weather.2. Nitrate movement and distribution were affected by fertilization methods also. Soil ammonia content was in the range of 2~5mg-kg~ during the study period, however, it was much higher than the range in fertilizer bands on 43d after fertilization. There was no clearly connection between soil ammonia content and fertilization methods.The nitrate leaching was reduced by ridge tillage since the infiltrated water was separated from the fertilizer band by the ridges. Fertilizer nitrate was decreased significantly by the barriers of the localized compaction and ridge. After the same amount of rainfall, the left nitrate in the application position under localized compaction and ridge with a 1.36g-cm-3 and it was 4.28 times of that under ridge fertilization. And the left nitrate was increased with the increasing bulk density of the barriers.In the Loess Plateau region, it is hardly for nitrate to leach below the root zone in field when the amount of total water both from natural rainfall and irrigation is smaller than or close to the annual average precipitation in corn growing period. Influenced by the supplied water, nitrate movement depths under flat, ridge and localized compaction and ridge fertilization were 65cm, 45cm, 45cm and >90cm, 75cm, 60cm, respectively, for the two years experiment. 80.80%, 90.51%, 92.02% the total nitrate accumulation were appeared in 0-50cm of the profile under flat, ridge and localized compaction and ridge fertilization in the first year. 47.00%, 77.06%, 90.32% of the total nitrate accumulation was appeared in the second year. The results support the hypothesis that the depth of nitrate transport can be reduced significantly by localized compaction and ridge fertilization.3. In the Lou soil region, the barriers with greater bulk density of localized compaction and ridge for good soil aggregate structure did not show a significant influence of nitrate transport and corn growth. There was no significant difference in yield between application methods with a given amount of applied fertilizer from the twoyear study under field conditions. However, the uptake amount of nitrogen was improved significantly by localized compaction and ridge, and the nitrogen use efficiency was increased by 9%. The nitrogen use efficiency of localized compaction and ridge was increased by 5%~6% compared...
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