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通过滴灌施用酸对土壤养分有效性、植物营养和产量方面具有潜在好处。把蕃茄栽种在114升衬有塑料的容器中,内装缺磷的石灰性壤土,每周通过滴灌施入磷素,如磷酸尿素(UP)(17-19-0)。分为四种浓度(每公顷0.20,40,80KgP)。其它两个处理是土壤条施三元过磷酸钙TSP)(0-20-0),每公顷(40KgP),在滴灌中施或不施硫酸尿素(US)(15-0-0-16)。硫酸尿素施用量相当于每公顷40KgUP-P处理的可滴定酸度。所有处理都施相当于每公顷100KgN的尿素。在植物移植后73天收获,称重和测定。土壤样品自滴孔以下0,10,20cm处各向下取5cm深,以测定pH,P,Fe,Mn和Zn。每公顷20Kg-P处理的果实和茎秆的产量比任何其它处理都高。每公顷施用80Kgup-p的处理中,磷素移至30cm深处。叶片中Zn的浓度随磷肥施用量增加而减少。酸的施用溶解了自然土壤中的P、Fe和Mn,而使植物在吸收US时其组织中的Fe、Mn达到最高量。硫酸尿素对土壤酸化作用以及Fe、Mn溶解比由UP引起的相同滴定酸度的效果明显。在缺少Fe、Mn的土壤中施用硫酸尿素较好。磷酸尿素看来是田间用于滴灌系统的一种有效磷肥。
Potential benefits of drip irrigation for soil nutrient availability, plant nutrition and yield. Tomatoes were planted in 114-L plastic lined containers containing phosphorus-deficient calcareous loam and weekly application of drip irrigation with phosphorus, such as phosphoric acid urea (UP) (17-19-0). Divided into four concentrations (0.20,40,80 KgP per hectare). The other two treatments were soil application of ternary superphosphate (TSP) (0-20-0) per hectare (40 KgP) with or without urea sulfate (15-0-0-16) . The urea sulfate application corresponds to 40 Kg UP-P titratable acidity per hectare. All treatments applied urea equivalent to 100 kgN ha per hectare. 73 days after the plant was harvested, weighed and assayed. Soil samples were taken 5 cm deep from 0, 10 and 20 cm below the drip hole to determine pH, P, Fe, Mn and Zn. The yield of fruits and stems per hectare at 20 Kg-P was higher than any other treatments. In the treatment of applying 80 kg ofup-p per hectare, phosphorus was moved to a depth of 30 cm. The concentration of Zn in leaves decreased with the increase of P application rate. Acid application solubilizes P, Fe and Mn in natural soils, allowing plants to achieve the highest levels of Fe and Mn in their tissues when they absorb US. The effect of urea sulfate on soil acidification and dissolution of Fe and Mn is more pronounced than the same titration acidity caused by UP. It is better to apply sulfuric acid urea in the soil lacking Fe, Mn. Phosphate urea appears to be an effective phosphate fertilizer for drip irrigation systems in the field.