Grasgroei en grondwaterstand : onderzoekingen over de betekenis van de grondwaterstand voor komkleigrasland

Results were discussed of experiments on watertable with permanent grassland and arable crops on river clay and on peat soil (grassland only). It is concluded that plant growth is affected by watertable in two ways: through the water supply and through the nitrogen supply. These factors derive from the water and air contents of the soil, which depend on watertable. A high moisture content promotes water supply of the plant but limits air content, thus promoting the bacterial denitrification of mineral nitrogen in the soil.

Grassland may respond to watertable in different ways. During drought water supply may be the determining factor and the highest gross yield will occur with high watertable. But with abundant rainfall the highest yields will occur with a low watertable since nitrogen supply is then the determining factor. Through changeable weather an optimum watertable could only be found during brief periods. In the long run the best results (also through risk of poaching) for clay grassland can be expected with a low watertable (100 cm or more) and with surface irrigation during drought.