Effect of clippings management on turfgrass sward productivity and nitrogen content in the clippings and soil

K. Kauer¹, H. Raave², R. Viiralt², T. Köster³, M. Noormets-Shansky²,T. Laidna², I. Keres², A. Parol² and A. Selge²

¹Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences,Kreutzwaldi 1, 51014 Tartu, Estonia; e-mail: karin.kauer@emu.ee
²Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences,Kreutzwaldi 1, 51014 Tartu, Estonia
³Agricultural Research Centre, Teaduse 4/6, 75501 Saku, Estonia

Abstract:

The maintenance of turfgrass sward includes mowing and fertilization. Every year turfgrass sward produces a sizeable amount of clippings containing large amounts of nutrients which will be available for plants during the decomposition process. The aim of this research was to study clippings decomposition speed, the effect of returned clippings to the turfgrass sward’s clippings yield and total nitrogen content in clippings and soil. The study was carried out on turfgrass sward (seed mixture composition Festuca rubra rubra 50% and Poa pratensis 50%). The turfgrass clippings were either removed after cutting or returned to the plots. The clippings yield and nitrogen content in the clippings were measured after every cutting. The soil samples from different plots were analyzed for total nitrogen at the beginning and the end of the growing season. The decomposition dynamics of clippings was studied using the litterbag technique. Also the nitrogen mineralization from decaying material and the concentration changes of cellulose and lignin were studied during 12 weeks.The results showed that the turfgrass clippings mass and the content of nitrogen decreasedduring the decomposition process very quickly. The degradation of cellulose takes place after about 30% of initial weight decomposition. During the 12 week study period we did not fix the beginning of lignin decomposition. Higher productivity was obtained in treatments where clippings were removed. N content did not differ in plant from plots where clippings returned or removed but N content in soil of plots with clippings returned decreased compared to N content in soil of plots where clippings were removed.

Key words:

cellulose, clippings, decomposition, lignin, N mineralization, turfgrass

Changes of lignin concentration and C:N in oilseed rape, wheat and clover residues during their decomposition in the soil

Z. Kriauciuniene², R. Velicka¹, S. Raudonius¹ and M. Rimkeviciene²

¹Department of Soil Management, Lithuanian University of Agriculture, Studentu 11,Akademija, LT-53361 Kaunas dist., Lithuania, e-mail: rimantas.velicka@lzuu.lt
²Experimental Station of Lithuanian University of Agriculture, Noreikiskės,LT-53363 Kaunas dist., Lithuania, e-mail: zita.kriauciuniene@lzuu.lt

Abstract:

Field experiments were conducted in 2003–2005 at the Experimental Station of the Lithuanian University of Agriculture to study the changes of lignin concentration and C:N in roots and top residues of winter and spring oilseed rape (Brassica napus L.), winter wheat (Triticum aestivum L.) and red clover (Trifolium pratense L.) after 14, 33, 63, 85 and 116 weeks of decomposition in the soil. Correlation between lignin concentration and amount of dry matter as well as the ratio of carbon and nitrogen in investigated crop residues were estimated.Investigation of crop residue decomposition during the period of 116 weeks showed thatstubble and roots of winter and spring oilseed rape decompose more slowly than their threshing remains, or stubble, and roots of winter wheat and red clover. Dry matter and lignin decomposed and the ratio of carbon and nitrogen in winter oilseed rape residues decreased more slowly than that of spring oilseed rape residues.The ratio of carbon and nitrogen in the decomposing crop residues decreased mostintensively during the 33–63 week period. After that, the concentration of lignin started to decrease, but its significant decline in all investigated crop residues was estimated after 116 weeks of decomposition. Lignin was most decomposed from its concentration peak in the stubble of red clover (37.9%) and least in winter oilseed rape roots (12.8%).Negative correlation between lignin concentration and dry matter amount and betweenlignin concentration and C:N was established in winter and spring oilseed rape, winter wheat and red clover top and root residues decomposing in the soil.

Key words: