水田土壤肥力现状及变化规律分析——以湖北省为例

2005～2009年测土配方施肥项目获取了大量数据,本文通过对湖北省2008年所获取的水田土壤养分数据进行抽样研究,系统分析鄂东、江汉平原、鄂东南、鄂东北、鄂中、鄂西北和鄂西南7个稻区的土壤肥力现状,并将其与第二次土壤普查时的数据进行比较,探讨水田土壤养分的变化规律及原因。结果表明,目前湖北省水稻土有机质、碱解氮、有效磷和速效钾含量及pH平均值分别为26.1 g kg-1、124.2 mg kg-1、13.1 mg kg-1、89.1 mg kg-1和6.3,主要分布范围分别为10～40 g kg-1、>90 mg kg-1、5～40 mg kg-1、50～150mg kg-1和5.0～7.5。各养分元素在不同稻区的分布均存在一定的差异,从全省来看,有机质含量具有东、南高,西、北低的分布特征;碱解氮具有西、南高,东、北低的特征;速效钾和pH具有西、北高,东、南低的特征;而有效磷没有表现出明显的区域分布规律。与第二次土壤普查相比,由于长期施用氮、磷肥和肥料用量不断增加以及秸秆还田面积和数量的增加,一方面促进了水稻土有机质、碱解氮和有效磷含量的提高,另一方面也加速了土壤的酸化;而钾肥用量的不足及高产水稻品种对钾素的大量吸收,也导致了土壤速效钾含量的下降。可见,在湖北省目前的稻区农业生产中,增加钾肥用量,合理调整氮、磷、钾肥的比例,并在进行秸秆还田的同时适当配施石灰,是实现水稻土肥力提高和防止土壤酸化的有效途径。本研究还说明,充分利用测土配方施肥项目的资料对土壤养分数据进行系统研究,可以获得对区域性土壤肥力现状及变化的全面认识。

STATUS QUO AND VARIATION OF SOIL FERTILITY IN PADDY FIELD —A CASE STUDY OF HUBEI PROVINCE

Through the project of soil testing and fertilizer recommendation in 2005~2009,a lot of data about soil nutrients in paddy fields were acquired.Based on the data obtained in Hubei 2008,status quo of the soil fertilities in seven rice producing regions of the province,namely,E’dong,Jianghan Pingyuan,E’dongnan,E’dongbei,E’zhong,E’xibei,and E’xinan were systematic analyzed and compared with the data obtained during the second national soil survey to explore laws and causes of the variation of soil nutrients in paddy field.Results show that presently the paddy soils in Hubei Province were 10~40 g kg-1 or 26.1 g kg-1 on average in organic matter,>90 mg kg-1 or 124.2 mg kg-1 on average in alkalystic N,5~40 mg kg-1 or 13.1 mg kg-1 on average in available P,and 50~150 mg kg-1 or 89.1 mg kg-1 on average in available K,and 5.0~7.5 in pH or 6.3 on average.The soil nutrients varied to a varying extent from region to region.In view of the province as a whole,the distribution of organic matter was characterized by being high in the east and south and low in the west and north,that of alkalystic N being high in the west and south and low in the east and north,and that of available K and pH both being high in the west and north and low in the east and south,while that of available P did not show any apparent rule.Compared with the findings of the second soil survey,the contents of organic matter,alkalystic N and available P increased while pH decreased as a result of long-term application of N and P fertilizers at an increasing rate and increased area and rate of straw incorporation.However,inadequate application rate of K fertilizer and the adoption of high K-demanding rice cultivar led to decrease in available K in the soil.Obviously in rice production in Hubei Province,to increase K application rate,to readjust the ratio of N∶ P∶ K rationally,and to lime the paddy fields at a proper rate while incorporating rice straw into the soil are effective approaches to raising soil fertility and preventing acidification of the paddy soils.The study also demonstrates that by making full use of the data of the project of soil testing and fertilizer recommendation and conducting systematic study of the soil nutrient data,it is feasible to obtain full knowledge of the status quo and variation of soil fertility of a region.