The effect of moisture stress on plant - available soil phosphorus
Blair, Sidney Stuart
In spite of the large amount of research on soil-plant-water systems during the past decade, little information is available on the influence of soil moisture or plant water stress on soil and fertilizer phosphorus availability. This is, in part, because much of the data from research dealing with the relationship between plant growth, soil moisture, and phosphorus availability have been inconclusive or even contradictory. In the western great plains area of North America and particularly throughout most of the agricultural area of Saskatchewan, soil moisture stress probably limits growth more than any other single factor. Equally significant, from the wealth of phosphate fertilizer trials, is the observation that crop responses to phosphate fertilizers is proportionately larger during dry than wet seasons. This suggests that the effective availability of soil phosphorus may decrease as soil moisture stress increases. It is not known definitely whether soil moisture stress changes the chemical availability of the soil phosphorus or results in a change of the rooting habit of the plant such that the plant is unable to fully exploit the total soil volume. The investigations reported in this manuscript have been designed to determine the effect of soil moisture tension and phosphorus concentration in the soil on phosphorus uptake by wheat.