Sprays and the environment

Silsoe Link, a grouping of Silsoe Research Institute, Silsoe College, Soil Survey and Land Research Centre and ADAS, held an open day on 22 February to address Agrochemicals: effective use and the environment. Their approach emphasises high technology solutions which appeal to farmers not convinced by extensive farming such as organic. It has been increasingly recognised that pesticide application has many inefficiencies. Meetings like this help to reduce the prospect of pollution from agrochemicals, but they still highlight the practical problems that high tech seeks to address. It has yet to be proved that intensive farming methods can reduce pollution from pesticides as compared with less intensive farming.

    Some aspects of current work, and the problems they pose are listed below:

Drift control using air-assistance

Air-assisted arable crop spraying can increase work rates and improve the timeliness of spray application. However, the risk of spray drift can increase beyond levels associated with conventional techniques if machine fittings are poorly defined. Previous work has shown the largest drift reductions occurred with high levels of air-assistance (jet speeds of 30m/s). Recent work at Silsoe Research Institute has shown that air-assistance can reduce drift, although measurements at low wind speeds suggest air-assistance can also increase drift. The Iargest drift reductions (around 60% ) occurred in high wind speeds.

Precision Farming

Traditional arable management has tended to assess fields as uniform entities, Precision farming takes into account local variability within a field. This allows for pesticide and fertiliser application rates to he modified according to need - which should reduce environmental problems and increase the economic returns. Precision farming is inherently- dependent on high technology, particularly, information technology (IT). Work done at Cranfield University suggests that the adoption of precision farming is likely to be an evolutionary process, with farms gradually improving their IT. Most of the component parts needed are sufficiently developed to be used in the near future by farmers.  

Water

The transport of pesticide residue to surface and ground water have increased in recent years. Scientists at ADAS Land Research Centre have studied the runoff of the herbicides isoproturon, mecoprop, chlorotoluron, linuron, dimethoate, atrazine and simazine from a mixture of land use types including arabIe, grassland and woodland. The estimated annual pesticide loss to surface waters was less than I% of the applied pesticide. Following conversion of arable land to natural regeneration set-aside, pesticide loss fell rapidly. Mixed agricultural systems within catchments, including less intensive land uses, had the lowest loss from pesticides.

For more information: Silsoe Link, Wrest Park, Silsoe, Bedford, MD45 4HS, Tel: (0)1525 860 000, Fax: (0)1525 860 156.

[This article first appeared in Pesticides News No.27, March 1995, page 19]