Premium
Effect of drought and irrigation on the fate of nitrogen applied to cut permanent grass swards in lysimeters: Experimental design and crop uptake
Author(s) -
Dowdell Rodney J.,
Webster Colin P.
Publication year - 1984
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740351008
Subject(s) - loam , lysimeter , irrigation , agronomy , soil water , nitrogen , dry matter , environmental science , chemistry , soil science , biology , organic chemistry
The effect of drought and irrigation on the yield and fertiliser nitrogen uptake by cut permanent grass swards was investigated using lysimeters containing monoliths (80 cm diam., 135 cm deep) of two soil types (Salop series, clay loam and Bromyard series, silt loam). Over the five summers 1977–81 swards were treated with four dressings of calcium nitrate at rates of 0 and 100 kg N ha −1 after each cut; in the first year, the nitrogen was labelled with 15 N. Rainfall equivalent to the long‐term average gave mean yields of 12.9 t dry matter ha −1 for Salop and 14.3 t dry matter ha −1 for Bromyard. Irrigation (to 120% of average summer rainfall) gave a non‐significant increase of 8–9% in herbage yield on both soils. When the average rainfall distribution was modified to create periods of drought for 4 weeks duration immediately before each cut and fertiliser application, yields were significantly depressed, by 12% on Salop soil and 20% on Bromyard soil. Adjustment of the drought so that cutting and nitrogen application fell mid‐way in the dry period resulted in only a small non‐significant depression of yield on both soils (yield 95–96% of average rainfall treatment). The recovery of applied 15 N labelled fertiliser in herbage during the first year of the experiment was in the range 45–47% for the Salop soil and 39–52% for the Bromyard soil. In the Salop soil the recovery of the labelled nitrogen was not significantly affected by imposition of drought conditions or by irrigation. However, in the Bromyard soil the drought treatment resulted in a significant reduction in the recovery of fertiliser nitrogen to 79% of that of the average rainfall treatment and irrigation increased the recovery to 106%. The contrasting results from the two soils was due to the imposed drought treatments which were more effective in creating differing soil water status in the Bromyard soil. This was due to its good drainage and lower water holding capacity. On both soils, fertiliser nitrogen constituted 53–60% of the total nitrogen content of the herbage. This experiment indicates that on clay soils with poor drainage status, the pattern of rainfall distribution has relatively little impact on the productivity of the sward and its utilisation of fertiliser nitrogen. On freely‐draining soils, however, heavy rainfall after drought following cutting and nitrogen application can substantially depress yield and fertiliser use.