Soil Drainage Influence on Biomass and Nitrogen Accumulation by Ryegrass
- William L. Stout and
- Ronald R. Schnabel
Grasslands are the basis for a stable agriculture in the Northeast USA. However, knowledge of interactive effects of soil drainage and N fertilization on grassland production in this region remains scant. Our objective was to quantify the effect of soil drainage on grassland biomass production and N accumulation. The study was conducted for 2 yr on a floodplain site in central Pennsylvania on two soils selected for extreme drainage conditions. Perennial ryegrass (Lolium perenne L. cv. Bastion) was treated with a split application (50% in mid-April, 50% in mid-July) of 0, 84, 168 and 252 kg N ha−1 of 15N depleted NH4NO3. Biweekly biomass samples were taken starting mid-May of each year and continuing until the grass headed and all herbage was removed from the plots. Plots were re-fertilized and monthly biomass sampling commenced at the end of August and continued until the end of October 31. Fertilizer nitrogen recovery was greatest in the first harvest after fertilization, irrespective of soil type or season. Peak fertilizer N recovery for spring growth was 50% on the well-drained soil and 32% on the poorly drained soil. In the summerfall growth period, peak fertilizer N recovery was 26% on the well-drained and 18% on the poorly drained soil. Biomass on the poorly drained soil was 26% less in the spring and 8% less in the summerfall periods compared with that of the well-drained soil. Overall, poor soil drainage conditions resulted in a 39 reduction in fertilizer N recovery and a 21% reduction in yield of perennial ryegrass.
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