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Publication Date

1981

Description

Predictions of the supply of soil nitrogen (N) to grass over a growing season requires an assessment of nitrate N plus am­monium N (1) present in the soil at the beginning of the season and (2) likely to be released from the potentially mineralizable organic N during the season. Although a number of methods have been proposed for predicting soil N supply, and in particular the component arising from the potentially mineralizable N, many are too time consuming for routine use, and others have not been proven effective over a range of soils. However, in recent studies, the measurement of nitrate N plus ammonium N, ex­tracted either (1) by boiling with 1M or 2M KC] or (2) by shaking with 0.05M Ba(OH)2, was found to account for 80% of the variation in the yield of Nin the herbage of perennial ryegrass (Lolium perenne L.) grown in pots on 21 soils under uniform en­vironmental conditions. The prediction of soil N supply in the field, at over 18 sites in the UK, was substantially improved when the results of soil analysis were adjusted by a factor, calculated for each site, based on mean values of temperature and soil­water status.

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Prediction of the Supply of Soil Nitrogen to Grass

Predictions of the supply of soil nitrogen (N) to grass over a growing season requires an assessment of nitrate N plus am­monium N (1) present in the soil at the beginning of the season and (2) likely to be released from the potentially mineralizable organic N during the season. Although a number of methods have been proposed for predicting soil N supply, and in particular the component arising from the potentially mineralizable N, many are too time consuming for routine use, and others have not been proven effective over a range of soils. However, in recent studies, the measurement of nitrate N plus ammonium N, ex­tracted either (1) by boiling with 1M or 2M KC] or (2) by shaking with 0.05M Ba(OH)2, was found to account for 80% of the variation in the yield of Nin the herbage of perennial ryegrass (Lolium perenne L.) grown in pots on 21 soils under uniform en­vironmental conditions. The prediction of soil N supply in the field, at over 18 sites in the UK, was substantially improved when the results of soil analysis were adjusted by a factor, calculated for each site, based on mean values of temperature and soil­water status.