Nutrient Release during Residue Decomposition of Weeds Mown at Different Times in a Persimmon Orchard

摘要

Decomposition and nutrient release of the residue subsequent to mowing weeds remain poorly understood in persimmon orchards of South Korea. The litterbags including various weed residues were deposited on the soil surface under the tree canopy to simulate the fate of weeds mowed on 13 May, 13 July, and 13 September 2011 and 2012. Rate of decomposition and nutrient release of the residues depended on different mowing times. Residual dry mass (DM) of the 13 May weeds decreased by 17 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:Verdana;"> style="font-family:Verdana;">21% of initial DM during 1 month and by 63 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:;" "=""> style="font-family:Verdana;">71% until 2 months after litterbag deposition, and they?released 51 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:Verdana;"> style="font-family:Verdana;">67% of nitrogen (N), 54 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:Verdana;"> style="font-family:Verdana;">55% of phosphorus (P), and 92 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:Verdana;"> style="font-family:Verdana;">94% of potassium (K) of respective initial amount until the first 2 months. The 13?July weeds rapidly decomposed during the first month, accounting for 51 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:Verdana;"> style="font-family:Verdana;">64% of DM and released 49 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:Verdana;"> style="font-family:Verdana;">67% of N, 27 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:Verdana;"> style="font-family:Verdana;">54% of P, and 76 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:Verdana;"> style="font-family:Verdana;">77% of K. When mowed on 13 September, the weed residue decomposed slower and?longer than the 13 May and 13 July weeds, losing 48 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:Verdana;"> style="font-family:Verdana;">51% style="font-family:Verdana;">of style="font-family:Verdana;">DM, 36 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:Verdana;"> style="font-family:Verdana;">39% style="font-family:Verdana;">of style="font-family:Verdana;"> N, 60 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:Verdana;"> style="font-family:Verdana;">64% style="font-family:Verdana;">of style="font-family:Verdana;"> P, and 70 style="font-family:Verdana;">% style="font-family:Verdana;">- style="font-family:;" "=""> style="font-family:Verdana;">77% style="font-family:Verdana;">of style="font-family:Verdana;"> K during the first 2 months but continuing an active decomposition even at 6 months after the deposition. The results indicated that time of supplemental fertilization should be adjusted depending on mowing times, and the mowing times be controlled to meet seasonal demand of persimmon trees for nutrients.