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Publication Date
1981
Description
In recent field trials on all-grass swards on clay soils, fertilizer rates of 480 kg/ha and higher showed distinct residual effects in the following year. This paper analyzes the considerable residual effects of one treatment on heavy clay soil over 2 experimental years, after very high rates of N had been applied during 3 pretreatment years (totaling 800 kg N or more/ha/yr). The residual effect was measured through the increase in yield over a reference treatment, at one rate of N application ( 40 kg N/ha/cut, totaling 200 and 240 kg N/ha in the first and second experimental years, respectively). Over the 3 pretreatment years the amount of N applied exceeded the amount of N harvested by 941 kg N /ha. The excess N was reflected in accumulation of mineral N in the soil. At the beginning of the first experimental year the soil contained 314 kg mineral N/ha against the reference treatment 21 kg N. The accumulated mineral N was nearly depleted by the end of the first season. A residual effect was evident at every cut, and over the whole growing season the increase in yield was 6 metric tons (t) dry matter (DM) and 199 kg N/ha. In the second experimental year, there was no difference in soil mineral N status of the treatments. Still, a residual effect was observed through an increase in yield of 1.1 t DM and 21 kg N/ha. The study showed that on heavy clay soils-despite N losses from the soil, especially through leaching in winter-part of the applied N may remain in the soil-plant ecosystem and will be available for grass growth in the following season(s).
Citation
PRins, W H., "Residual Effects of Two Years of Very High Nitrogen Applications on Clay Soil under Grass in a Humid Temperate Climate" (1981). IGC Proceedings (1981-2023). 10.
(URL: https://uknowledge.uky.edu/igc/1981/section3/10)
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Residual Effects of Two Years of Very High Nitrogen Applications on Clay Soil under Grass in a Humid Temperate Climate
In recent field trials on all-grass swards on clay soils, fertilizer rates of 480 kg/ha and higher showed distinct residual effects in the following year. This paper analyzes the considerable residual effects of one treatment on heavy clay soil over 2 experimental years, after very high rates of N had been applied during 3 pretreatment years (totaling 800 kg N or more/ha/yr). The residual effect was measured through the increase in yield over a reference treatment, at one rate of N application ( 40 kg N/ha/cut, totaling 200 and 240 kg N/ha in the first and second experimental years, respectively). Over the 3 pretreatment years the amount of N applied exceeded the amount of N harvested by 941 kg N /ha. The excess N was reflected in accumulation of mineral N in the soil. At the beginning of the first experimental year the soil contained 314 kg mineral N/ha against the reference treatment 21 kg N. The accumulated mineral N was nearly depleted by the end of the first season. A residual effect was evident at every cut, and over the whole growing season the increase in yield was 6 metric tons (t) dry matter (DM) and 199 kg N/ha. In the second experimental year, there was no difference in soil mineral N status of the treatments. Still, a residual effect was observed through an increase in yield of 1.1 t DM and 21 kg N/ha. The study showed that on heavy clay soils-despite N losses from the soil, especially through leaching in winter-part of the applied N may remain in the soil-plant ecosystem and will be available for grass growth in the following season(s).
