Saturday, 15 July 2006

Study on Spatial Variance of Soil Nutrients for Moso Bamboo Forest of fertilization.

Xiaomin Guo1, Dekui Niu2, Xi Guo2, Guoshi Zhang1, Bin Zhang1, Dongnan Hu1, and Fang Chen (Corresponding Author)3. (1) College of Forestry, Jiangxi Agricultural University, Jiangxi Province, China, Nanchang, 330045, China, (2) College of Land Resource & Environment, Jiangxi Agricultural University, Jiangxi Province, China, Nanchang, 330045, China, (3) Wuhan Botanical Garden, Chinese Academy of Sciences,, Hubei of China, Wuhan, 430074, China

Using the geo-statistics semi-variance function combined with the GIS technique and the systematic approach for soil nutrients status evaluation to quantitatively study the soil nutrient spatial variance characteristics in Fengxin and Jing'an. Results showed that: soil nutrient distribution in each trial zone is accord with the semi-variance structure. Most of them are fit the spherical model. The self-correlative distance of the soil nutrients are vary form 32m to 398m and form 24m to 120m in the trial zone of Fengxin and Jing' an respectively. The sampling distance of 15-20m may satisfy the requirements of the soil spatial variance evaluation of bamboo forest. The spatial relativity of N, P, K is small, but the spatial variance is larger than Ca, B, Fe,Mn and Mg. The value of the fractal dimension of the soil nutrients in the bamboo forest of Fengxin and Jing'an take turn as: Cu> Mn> total P> Zn> P> N> Fe> Mg> S> OM> Ca> B> total K> total N. is B> S> total N> N> P> K> Mg> total P> OM> Zn> Cu> Ca> Fe> total K> Mn respectively. Long-term of fertilizing could promote and improve the homogenization of the spatial distribution of the soil nutrients. In the common year, the spatial distribution of the soil nutrients is more complicated and the homogeneousness of the distribution of the soil nutrients is much lower. The structural variance of the soil nutrients is greater than the random variance of the soil nutrients, and the influence of the natural factors of soil (soil minerals and landform) is bigger than the influence of the artificial factors (cultivation level and fertilization). The factors that caused the difference of the spatial distribution of soil nutrients between Fengxin and Jing'an are fertilization and erosion. The easy ambulate of the N, K; the spatial distribute patterns of different density bamboo forests and the year cycle; random factors such as the erosion and the spatial difference of erosion intensity; balance fertilization lead to the utilize way of the inlaid distribution of the different testing areas are all reduced the distribution of the N, K, and make the spatial relative measure of available N and available K. So, with the deflective soil nutrients which with bigger variance, more fertilization, and has long fertilizer history should make propriety adjust when making the recommendation of balance fertilization. We must consider the spatial variation condition of the soil nutrients as well as consider the average content of the soil nutrients so as to improve the precision of balance fertilization. Otherwise, it would be hard to obtain high yields or result in fertilizers wasting and environment pollution.

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