Changes in productivity of grassland with ageing

<p/>The productivity of grassland may change greatly with ageing. Frequently, a productive ley period, occurring in the first time after (re)seeding, is followed by a period in which productivity decreases. Under conditions favourable to grassland this may be temporary. A production level finally can be attained almost equalling that of young reseeded grassland, but mostly not that of liberally fertilized grassland sown in arable crop soil.<p/>Especially changes in organic matter content in the soil, activity of the earthworm population, the occurrence of "soil sickness" and an insufficient longevity of the sown species can be involved.<p/>Grassland with a high clover percentage in the sward may react differently to these changes than grassland with a low clover content. In the present research usually no clovers were sown.<p/>A decrease in the organic matter content of the soil had a negative effect on productivity; this negative influence was evident almost from sowing onwards, decreased gradually and asymptotically with ageing and could be compensated for the most part by N fertilizing.<p/>Sowing grass in an arable crop soil, with a liberal N dressing resulted in more productive grassland than reseeding. This difference in productivity ,was only temporary.<p/>A low earthworm population caused mat formation, an unfavourable physical condition and a lower gross yield.<p/>Disappearance of the sown grass species and varieties may result in a decreasing productivity