Effect of lime on soil nitrogen uptake by a ryegrass-white clover pasture

The effect of liming (7.25 t/ha) on soil nitrogen (N) uptake was measured in a mixed rye-grass-white clover pasture over a 2-year period. Liming significantly increased ryegrass dry matter (DM) production by 8% but had no significant effect on clover or total DM production. Liming significantly increased the amount of soil N taken up by grass, and total soil N uptake increased by 50 kg N/ha over 2 years. The proportion of total soil N taken up by clover was positively related to the clover composition of the pasture, and was greatest in summer (30-40%) and least in winter (5-10%). The proportion of clover N derived from the soil ranged from 30 to 60%. Liming had no effect on the proportion of soil N taken up by clover or the proportion of clover N derived from the soil.