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THE EFFECT OF REPEATED FIELD APPLICATIONS OF FOUR HERBICIDES ON THE EVOLUTION OF CARBON DIOXIDE AND MINERALIZATION OF NITROGEN IN SOIL
Author(s) -
GROSSBARD E.
Publication year - 1971
Publication title -
weed research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 74
eISSN - 1365-3180
pISSN - 0043-1737
DOI - 10.1111/j.1365-3180.1971.tb01009.x
Subject(s) - simazine , mcpa , mineralization (soil science) , chemistry , soil water , carbon dioxide , environmental chemistry , nitrogen , organic matter , soil respiration , agronomy , nitrogen cycle , zoology , weed control , environmental science , pesticide , soil science , biology , atrazine , organic chemistry
Summary The effect of repeated annual applications over 7‐8 years of MCPA, triallate, simazine and linuron to field plots on the evolution of CO 2 and mineralization of nitrogen in soil samples incubated in the laboratory is described. The plots were either cropped and treated with standard doses, or uncropped and sprayed with doses 3‐4 times above the level used in agricultural practice. While the applications of MCPA and tri‐allate did not exert any inhibitory effects in soils from the uncropped plots those of simazine and linuron led to a lowering in CO 2 output in several instances and in mineral N on infrequent occasions. These effects are assumed to be the result of a difference in the content of easily‐degradable organic matter between the treated plots and the controls. A direct anti‐microbial action of the two herbicides is not very probable because in laboratory experiments with simazine up to 512 ppm the output of CO 2 and the mineralization of N was not affected while linuron at 500 ppm gave only a minor depression in CO 2 evolution. Effects on soil fertility are unknown but seem unlikely in view of the small extent and infrequency of the reductions observed. On the cropped plots the MCPA and tri‐allate treatment showed no effects. With linuron and simazine a significant lowering in respiration and mineralization of N occurred on single occasions only, during a 5‐year period.