滴灌条件下施镁的生物有效性及其移动分布

Effects of Magnesium Fertilizer and its Distribution under Drip Irrigation

[目的]以番茄为供试植物,探讨在赤红壤中滴灌施肥条件下镁对作物生长的影响以及滴施镁肥后镁在土壤中水平方向和垂直方向上的移动规律.[方法]以硫酸镁为镁源,通过滴灌系统施入,设3个不同用量处理,在不同的生长时期测定.[结果]随着施镁量（0～6g/盆）的增加,与CK相比,施用镁肥能增加植株的干重和果实的鲜重,而滴施镁肥各处理的番茄株高增加33.69％～37.19％,其中D6-4处理（施镁量4g/盆）植株干重增加28.55％,达到0.05水平显著差异.在整个生长期滴施镁肥各处理的相对叶绿素和植株叶片含镁量都能保持在较高的水平.在生长中后期,随着滴施镁肥量的增加,滴施镁肥各处理的植株叶片含镁量增加31.0％ ～ 101.6％,与CK相比达到0.05显著水平.土柱模拟滴施硫酸镁试验结果表明,滴施3个浓度水平的硫酸镁后,土层交换性镁含量在水平方向上都呈先递减后递增的趋势,在10～ 15 cm土层镁含量达到最低,其后在15 cm以下的土层中镁含量逐渐升高;而在垂直方向上都呈先急剧减少然后缓慢增加的趋势,其中在0～5、5 ～ 10 cm土层中交换性镁含量的下降幅度较大,在10 cm以下土层中交换性镁含量变化趋于平缓.[结论]与不施镁肥处理相比,施用镁肥能促进番茄的生长.滴施不同浓度的镁肥,土层交换性镁含量在水平方向上呈先递减后递增的趋势,在垂直方向上呈先急剧减少然后缓慢增加的趋势.

[Objective] The research aimed to study the influence of magnesium on growth of tomato under drip fertigation and the horizontal and vertical distribution of exchangeable magnesium in lateritic soil after the drip fertilization were studied.[Method]With magnesium sulfate as a source of magnesium,through a drip irrigation system,setting up three different dosage treatments,the required data in different growth periods was determined.[Result] Compared with CK,with the increase of the amount of magnesium application （from 0 to 6 g/pot）,plant height and dry weight increased by 33.69％-37.19％ and 28.55％,and leaf magnesium content increased by 31.0％-101.6％ after middle growth stage,but didn ＇ t exist significant differences in all magnesium treatments.In addition,relative leaf chlorophyll and leaf Mg content could hold at a high level in the growth period.The higher dry weight treatment was D6-4（4 g/pot）.An indoor simulating experiment conducted with repacked soil columns under drip fertigation showed that,after fertilizing magnesium sulfate,the content of exchangeable magnesium first decreased and then increased at horizontal direction,among which the lowest exchangeable magnesium content was at the layer of 10-15 cm,and after the layer of 15 cm gradually increased.tn uprightness direction,such change trend of exchangeable magnesium was firstly distinctly declined,and then slowly increased,which sharply slowed down from 0-5 cm to 5-10 cm layers,and slightly changed after 10 cm near dripper.[Conclusion] Compared with no fertilizer and magnesium fertilizer,magnesium fertilizer could promote the growth of tomato.After drips fertigation of different concentrations of magnesium fertilizer,the trend of soil layer in the exchangeable magnesium content in horizontal direction was decreasing after increasing,and had a sharp drop in vertical direction and then slowly increase trend.