Time serial change of grain yield and its impact factors in Hailun,Heilongjiang Province;

Digitization of grain yield and distribution information in farmland;

Evaluation methods to climate years for grain yield in Gansu province;

The relationship between grain output and fertilizer input in wheat-corn cropping area of the Huang-Huai-Hai plain;

China s grain output has been fluctuating since 1978.

The wavelet analysis has been used to analyze the grain output in Shandong province from 1949 to 2005.

Review of impacts of no-tillage on crop yield and economic benefit;

Much forest harvesting resulted in the diversification of region climate and consequently brought in the diversification of crop yield.

Therefore,it is of great significance to keep certain areas of farmland for crop yield.

Combination forecasting model will be applied to forecast the grain production of China,in order to make the result more exact.

There are some limitations in the normal gray incidence degree more or less,this paper put forward a new revised gray incidence degree according to these limitations,and applies it in the agricultural system of a county in Songhuajiang-nenjiang basin,studies the relation between the grain production and factors influencing quantity,on this basis,the countermeasures are presented.

In order to know the grain production of the future,according to the grey system theory,this article uses the data of the grain production from 2000 to 2004 of Henan province,exert the method of grey forecast model GM(1,1),making a dynamic forecast on the future grain production of Henan province,and provides the scientific decision-making thereunder for the development of Henan province.

Effects of dietary energy on release of FSH and LH in prepubertal gilts;