华南冬瓜主产区土壤镁素淋洗损失规律

Study on Soil Magnesium Leaching Loss in Main Producing Areas of Wax Gourd in South China

本研究在华南典型冬瓜种植区开展了为期两年的田间试验,试验共设置6个处理,分别是农户常规施肥(CK)、化肥减量(Mg0)及在化肥减量基础上增施30、60、90、120 kg/hm^(2) Mg O(Mg1、Mg2、Mg3、Mg4),通过测定不同处理冬瓜种植期内土壤Mg、N、P、K和Ca淋洗差异,评估土壤Mg营养平衡,分析不同土壤及环境因子对Mg淋洗损失的影响,旨在探明土壤Mg淋洗损失特点,明确加剧土壤Mg淋洗损失的关键因子。结果表明,与CK处理相比,化肥减量措施下,土壤Mg、N、P、K和Ca累积淋洗量分别减少36.19%~40.50%、29.68%~36.86%、21.14%~46.74%、39.65%~42.83%和29.65%~48.60%。外源添加镁肥会增加土壤Mg累积淋洗量,同时也提高了土壤交换性镁含量,与Mg0处理相比,Mg1、Mg2、Mg3和Mg4处理Mg累积淋失量分别显著增加了42.46%~78.79%、53.94%~69.92%、78.92%~101.83%、133.07%~134.37%;Mg3和Mg4处理下土壤交换性镁含量分别增加了69.02%~81.10%和68.70%~78.54%,土壤阳离子交换量分别提高了9.44%~34.93%和14.26%~38.31%。采用随机森林模型进行Mg淋洗影响因素相对重要性分析发现,土壤交换性镁含量、降雨量、阳离子交换量、交换性钙和速效钾含量均会显著影响土壤Mg的淋洗。因此,在华南冬瓜种植区开展Mg营养管理时,应注重施用缓效镁肥,同时注重其他养分平衡,以提高补Mg效率。

In this study,a two-year field experiment was conducted in a typical wax gourd growing area in South China,in which six treatments were set up:conventional fertilizer(CK),fertilizer reduction(Mg0),and additional application of 30,60,90,120 kg/hm^(2) MgO(Mg1,Mg2,Mg3,Mg4)on the basis of Mg0.By measuring the differences of soil Mg,nitrogen(N),phosphorus(P),potassium(K)and calcium(Ca)leaching in different treatments during the planting period of wax gourd,evaluating soil Mg nutrient balance,and analyzing the effects of different soil and environmental factors on soil Mg leaching loss,the effects of different nutrient management measures on soil Mg leaching loss and identify the key factors that increase soil Mg leaching loss were explored.The results showed that the cumulative leaching amounts of Mg,N,P,K and Ca under Mg0 were reduced by 36.19%–40.50%,29.68%–36.86%,21.14%–46.74%,39.65%–42.83%and 29.65%–48.60%compared with CK,respectively.After the application of Mg fertilizer,the cumulative leaching amounts of Mg was increased by 42.46%–78.79%,53.94%–69.92%,78.92%–101.83%and 133.07%–134.37%in Mg1,Mg2,Mg3 and Mg4 compared with Mg0,and the exchangeable Mg content was increased by 69.02%–81.10%and 68.70%–78.54%in Mg3 and Mg4 compared with Mg0.In addition,soil cation exchange capacity(CEC)of Mg3 and Mg4 increased by 9.44%–34.93%and 14.26%–38.31%compared with Mg0,respectively.The contents of soil exchangeable Mg,rainfall,soil CEC,exchangeable Ca and available K significantly affected the leaching of soil Mg.In conclusion,in soil Mg nutrition management in wax gourd growing area of South China,attention should be paid to the application of slow Mg fertilizer and the balanced application of other fertilizers to reduce the leaching loss of Mg.