| dc.description.abstract | Plots in 3 replicates at Mwea Tebere Cotton
Research Station, on which cotton had been planted 1n
October 1980 were treated with technical DDT at various
application rates and at different times of the year.
The soil and cotton leaves were then sampled over a
period of 4-5 months for the determination of the
levels of pesticide residues remaining. From the data
obtained the persistence of P,P'-DDT and related compounds
was determined. Rainfall and a1r temperatures were
recorded through the period of study.
Replicate 1, was treated in February 1981, when
the area was hot and dry while replicate 3 and 4 were
treated with insecricide in April, during the rains
Replicate 2 was left untreated to act as a control.
The rate of loss of P,P'-DDT and it's related
compounds from soils at Mwea Tebere was found to be rapid
under aJl the various climatic condi~ions operating during
the course of thi~ research programm~. The losses seem to
occur by a 2 step process, consistini~of a fast initial
stage followed by a slower second stage. The times
taken for the loss af various percentages of the initial
amount of pesticide applied are calculated.
The loss of P,P'-DDT, O,P'-DDT, P,P'-DDD ant
P,P'-DDE from cotton leaves was found to take place
rapidly and preferential loss of pesticide from the
upper leaves was shown to take place under all climatic
conditions observed.
The data resulting from this study are analysed
and discussed in relation to the various climatic
conditions operating d~ring the period of the study | en |
