Js. Bailey et al., Use of precision agriculture technology to investigate spatial variabilityin nitrogen yields in cut grassland, CHEMOSPHERE, 42(2), 2001, pp. 131-140
Spatial variability in N uptake and utilisation by swards within uniformly
managed held units could be responsible for a significant proportion of the
NH3, N2O, NO3- and NOx (NO and NO2) 'pollutants' generated by agriculture
and released to the environment. An investigation was commenced, therefore,
to quantify, map and explain the spatial variability in sward N yield in a
'large' silage field and to assess the potential for managing this variabi
lity using some of the latest precision agriculture technology. Sward dry m
atter (DM) and N yields were predicted from the results of plant tissue ana
lyses using mathematical models. Sward N yields were found to vary greatly
across the field seemingly because of differences in net soil N mineralisat
ion, but the pattern of variability appeared to remain constant with time.
Conventional soil analysis of a range of soil chemical and physical propert
ies, however, failed to explain this variability. It was concluded that the
N-yield distribution map might be used in place of soil analysis as the ba
sis for varying the rates of N application to different parts of the held w
ith the twin objectives of maximising fertiliser use efficiency and minimis
ing N emissions to air and water. (C) 2000 Elsevier Science Ltd. All rights
reserved.