Publication Date:
2016-07-22
Description:
Background and aims The ability of grass mulches to inhibit weed performance has been linked to their limitations on nitrogen availability to the weeds. Fungal translocation of N from the soil to the surface mulch has been confirmed in laboratories, but this mechanism has not been documented under field conditions. Methods Experiments used 15 N (NH 4 ) 2 SO 4 , 99.7 at.%, which was uniformly injected below the soil surface at a rate of 1 mg 15 N kg −1 soil. Some plots were treated with a fungicide (Captan) every 2 weeks after injection, while others were not treated. Nitrogen transfer was monitored by measuring levels in surface residue, soybean tissue, and extractable soil inorganic N pools. Results Despite the N release from the cereal rye ( Secale cereale L.) tissues ranging from 15 to 50 kg N ha −1 , there was a detectable increase in 15 N enrichment of 10–15 % in the cereal rye tissue. Six weeks after injection, tissue from the plots not treated with fungicide contained 36 % more 15 N. Conclusions The increased 15 N enrichment in the cereal rye mulch supports laboratory observations that soil inorganic N is translocated into surface mulch via fungal mechanisms. These findings illustrate microbial-mediated sinks for nitrogen in cereal rye mulches in no-till soybean production systems.
Print ISSN:
0032-079X
Electronic ISSN:
1573-5036
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
