The effect of organic mulches on yields and phosphorus utilization by plants in acid soils

Summary The effect of organic mulches on the yields of plants and on their utilization of applied phosphate was determined by using a variety of crops grown in a Manitoba acid soil. The plants gave larger yields and utilized a greater portion of applied phosphate when the soil was mulched than when unmulched. The increased utilization of applied phosphate by the plants grown in the mulched soils appeared to be due to two factors. First, mulching resulted in a greater concentration of roots near the soil surface, thus enabling the plants to utilize the surface-applied phosphate. Approximately 60 to 97 per cent of the effect of mulch in increasing yield and phosphate utilization could be attributed to the above factor. Secondly, mulching tended to increase the downward movement of phosphorus and decrease the amount of phosphorus fixed by the soils