Fertility requirements of pastures and their diagnosis

The basic aim in an efficient system of pastoral farming must be the highest possible sustained yields of animal products consistent with the maintenance and improvement of soil fertility. This involves the maximum production of dry matter of the right quality. This paper does not deal exhaustively with quality, but it is necessary to remind ourselves that quantity and quality are not necessarily highly correlated. Both yield and quality of dry matter depend on the soil, climate, herbage species and strains, stock and pasture management and fertiliser applications. Most of the factors influencing soil fertility can be classified as biological, physical, or chemical. This paper deals primarily with chemical factors. I intend to state what I consider the basic principles underlying herbage production in New Zealand insofar as nutrients are concerned and then consider the assessment of the nutrient deficiencies and requirements of various soils by empirical methods and from more basic knowledge