Effect of mulch on N-content in soil, N-uptake, and growth of lettuce

Lettuce (cv. Prosper) was cultivated in five plantings at the experimental farm of Hohenheim University, Germany, in 1993 and 1994. Three different mulch treatments were chosen: no mulch, paper mulch, and PE-mulch. Samples were collected in seven days intervals. It could be demonstrated that there were differences between the mulch treatments in nitrogen mineralisation during the growing period. The increase of NO3- and NH4+ nitrogen was much faster for the treatments no mulch and paper mulch than for PE-mulch. For paper mulch and PE-mulch the level of NO3- and NH4+ nitrogen was higher than for no mulch. It was possible to show differences between the treatments for the plant development recorded as fresh weight, root length, and distribution of roots. But there was no direct correlation to the NO3- and NH4+ nitrogen in the soil.