| By conducting the succeeding farmer survey, the sampling and analysis of soil, crop, and irrigation water, and the monitoring dynamics of nitrate in groundwater, this paper, taking the typical intensive cropping systems wheat-maize double cropping system, greenhouse vegetable, and orchard as the research object, has particularly analyzed the changes of soil quality in different intensive cropping systems, the effects of nitrogen balance on soil nitrate-N residue and ground water nitrate concentration, and the characteristics of nitrogen flows and the ways of nitrogen losses, it has also been discussed that the crop yield response to the reducing application for nitrogen fertilizer and the capacity of reducing nitrogen fertilizer rate to lessen nitrate leakage.The main crops cultivated in Huimin county, Shandong province were wheat, maize, cotton, orchard tree, greenhouse vegetable, and open air field vegetable. The nitrogen fertilizer rate applied on these crops 340, 234, 234, 519, 1382, and 627 kg hm-2 N, and 282, 1142, and 211 kg hm~2 N were also added to orchard tree, greenhouse vegetable, and open air field vegetable as manure. These input were far exceeded the demand of crops for nitrogen.The typical surveys show that much nutrients accumulated in soil of greenhouse vegetable field, especially for nitrate-N and soil available phosphorus. Nitrate-N amounted to 1389.8 kg hm-2 N in 0-90 cm soil layer, which come to 5.6 folds of that in same soil layer in wheat-maize cropping system, and the concentration of available phosphorus in 0-90cm soil layer of greenhouse vegetable field come to 8.4 folds of that in wheat-maize cropping system. Severe leakage also occurred on the accumulative nutrient in greenhouse vegetable soil. The content of soil organic matter, total N, available Fe, Mn, Cu, and Zn in greenhouse vegetable field were significantly higher than these in wheat-maize field, same as the soil content of Cd which amounted to 2.8 folds as in grain field. The content of Cd was positively correlated with soil available P, it proposed that excessive application of P fertilization was the main cause inducing accumulation of Cd in soil. Soil electrical conductivity was positively correlated with nitrate content, while pH decreasingly related to nitrate with power function, these indicted that intensive accumulation of NO3--N in soil was the main factor induced soil salinization and acidification. Nitrogen inputs in greenhouse vegetable with chemical fertilizer, manure, and irrigation water were 1358 kg hm-2 N, 1881 kg hm-2 N, and 402 kg hm-2 N, respectively, these summed up 3656 kg hm-2 N. Nitrogen inputs in greenhouse vegetable through chemical fertilizer, manure, and irrigation and the total N input were 2.5, 37.5, 83.8, and 5.8 times of that as in wheat-maize field, and 2.1, 10.4, 68.2, and 4.2 times as in orchard. Nitrogen outputs by crop harvest in these 3 systems were 329 kg hm-2 N, 280 kg hm-2 N, and 121 kg hm-2 N, respectively, while nitrogen surplus were 3327 kg hm-2 N, 349 kg hm-2 N, and 746 kg hm-2 N at the same system order, respectively. A nitrate-N accumulation of 1165 kg hm-2 N, 227-275 kg hm-2 N, and 613 kg hm'2 N occurred in 0-90 cm soil layer in these 3 systems, meanwhile a accumulation of 1028 kg hm-2 N, 213-249 kg hm-2 N, and 976 kg hm'2 N did in 90-180 cm soil layer. Aobvious nitrate leakage existed in all 3 systems. Nitrate contamination in <15m shallow ground was much severe in greenhouse vegetable area, nitrate-N concentration of 99 percent samples exceeded the nitrate maximum control level lOmgNL-1, while it was only 5 percent in orchard field. Groundwater nitrate-N concentration decreased with well depth with a exponential function.Nitrogen input in household level was 462 to 848 kg hm-2 N, of which 79-92% come from chemical fertilizer and manure. Nitrogen output was between 45 to 132 kg hm-2 N. Subtract of output from input come to a N surplus of 394-744 kg hm-2 N at household level, which was mainly constituted from soil surface surplus, come to 277-673 kg hm-2 N. Th...
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