Abstract
Theoretical analysis for asking optimum amount of side-dressing application and its aplication to spring-sown chinese cabbage were conducted in order to obtain uniform product and higt quality yield by precisely controlling amount of fertilizer distribution according to the individual crop growth condition at the course of growth.
A crop fresh weight W was assumed to be the estimation function of the crop growth volume and statistical field distribution of the crop weight represented to be the normal distribution N (μ, σ2)≈N(W, s2), When fertilizing function correspond to degree of the individual crop weight was decided to be y=f(W), the total amount of fertilizer distribution per plant population n, Y was shown as follows:
Y=n∫∞0N(W, s2)f(W)dW
Now, f(W) was decided to be 0 at 5% range of it and g(W)=aW+b(a<0) at the rest of it. Therefore, the coefficient a, b under the condition of W=48.8gf, s=20.27gf was shown as following equation:
47.6a+0.95b=42
As the crop weight W was difficult to measure directly by non-destructive method, the crop width parralleled to the row direction L was introduced as the variable to estimate the crop weight by the result of the regression analysis. At the experiment of spring-sown chinese cabbage cultivation, the regression line equation of W=4L-70.4(r=0.88**) was obtained and four treatment plots described below were considered and accepted to fertilize crops correspond to the crop growth
A: even fertilizer plot (y=42gf)
B: variant fertilizer plots (21.5cm≤L≤38cm)
I-g(L)=-0.8L+68.3(a=-0.2, b=54.24)
II-g(L)=-1.6L+92.4(a=-0.4, b=64.26)
III-g(L)=-2.4L+116.5(a=-0.6, b=74.27)
In case of giving the lighter crop much fertilizer and the heavier crop less fertilizer, the more difference among the applied amount of fertilizer distribution there was, the less difference among the yield (total crop weight and eatable weight) there was. The uniform product would be able to be resulted by the alternative fertilizer treatment.
The theoretical fertilizing function to minimize the difference among the crop yield was finally obtained as g(L)=-3.6L+152.7, however, which should be confirmed by the actual cultivation experiment.
