菜地和一般农田土壤主要养分累积的差异

选取不同类型菜地和一般农田 ,测定了 0～ 2 0 0cm土壤剖面的有机质、全氮、硝态氮、铵态氮、速效磷、速效钾等主要养分含量及其分布 .结果表明 ,菜地土壤中养分大量累积 ,其中硝态氮和速效磷累积程度较高 .大棚和露天菜地 0～ 2 0 0cm土层的硝态氮累积总量分别为 15 2 0 .9kg·hm-2 和 135 8.8kg·hm-2 ,比农田高出 5 .2和 4.5倍 ;速效磷分别为 978.1kg·hm-2 和 5 0 3.3kg·hm-2 ,比农田高出 6 .2和 2 .7倍 .而其它养分增加相对较少 .有机质累积总量分别为 2 80 .5Mg·hm-2 和 2 6 9.3Mg·hm-2 ,比一般农田高出 12 .5 %和 8.0 % ;全氮分别为 37.5Mg·hm-2 和 32 .7Mg·hm-2 ,比农田高出 36 .2 %和 18.6 % ;铵态氮分别为 2 11.5kg·hm-2 和 197.8kg·hm-2 ,比农田高出 2 9.6 %和 2 1.2 % ;速效钾分别为 6 5 6 7.8kg·hm-2 和 5 5 2 3 .6kg·hm-2 ,比农田高出 30 .6 %和 9.8% .此外 ,菜地土壤中累积的养分不仅分布在表层 ,在深层土壤也大量存在 ,说明菜地存在严重的养分淋溶现象 .

Difference of several major nutrients accumulation in vegetable and cereal crop soils

Investigation and determination of several major nutrients in different types of vegetable and cereal crop soils were carried out in the Guanzhong Plain in Shaanxi Province. The results showed that organic matter, nitrogen, phosphorus and potassium accumulated more in the 0-200 cm profile of vegetable soils than in that of cereal crop soils. However, the accumulation degrees were different with different nutrient forms. The total amount of nitrate-N in the soil profile of plastic greenhouse and usual vegetable field was 1520.9 kg.hm-2 and 1358.8 kg.hm-2, being 5.2 and 4.5 times higher than that in the cereal crop fields respectively. The total amount of available-P was respectively 978.1 kg.hm-2 and 503.3 kg.hm-2 in the two vegetable soils, and 136.2 kg.hm-2 in cereal crop soils, and the former two were 6.2 and 2.7 times higher than the latter. For other nutrients, organic matter in cereal crop soil was 249.4 Mg.hm-2, and that in plastic greenhouse and usual vegetable soil was 280.5 Mg.hm-2 and 269.3 Mg.hm-2, respectively, which were only 12.5% and 8.0% higher than that in cereal crop soils. The total-N in plastic greenhouse and usual vegetable soils was 37.5 Mg.hm-2 and 32.7 Mg.hm-2, which was 36.2% and 18.6% higher than that (27.5 Mg.hm-2) in cereal crop soils, respectively. The ammonium-N was 211.5 kg.hm-2 and 197.8 kg.hm-2, which was 29.6% and 21.2% higher than that (163.2 kg.hm-2) in cereal crop soils. The available-K was 6567.8 kg.hm-2 and 5523.6 kg.hm-2, which was 30.6% and 9.8% higher than that (5029.7 kg.hm-2) in cereal crop soils. Furthermore, serious nutrient leaching occurred in vegetable soil profiles due to over-fertilization and irrigation.