There are many reasons for farmers moving into chemical agriculture as a result of the development of growth regulators, a product of World War II technology. This development gave man a new dimension in his fight to control pest of animals and plants. The new technology was adopted quickly and many years of use followed without the needed conscience and research to monitor possible detrimental effects on the environment. Disease and insect resistance developed and concern was increasing relative to broad usage of pesticides, their involvement in the food chain and effects on other organisms.

Adoption of chemicals as an aid in agricultural production was very rapid. This was a method of substituting capital for labour , time and to ensure protection beyond that available with previous chemical and biological control. Continuous or near continuous cultivation of crops produced a specific monoculture previously not experienced by farmers. Economic pressures on producer continue to increase demanding volume in order to continue farming. These factors created a situation requiring the use of commercial fertilizers, herbicides, insecticides, and fungicides which are still present on the agricultural scene at an increasing intensity.

Many changes were taking place with the farmer as well. Better education, a concern for land and its associated life forms produced a practical environmentalist working in concert with nature while producing crops and livestock.

Farmers found with commercial fertilizers, crop yields were increased. Larger amounts of crop residues were returned to the soil for erosion protection and to decrease soil degradation. Less soil damage occurred by growing a vigorous crop as compared to nutritionally deficient low yielding plants.

A new system moved onto the farms in the 1960’s called “no tillage”. This system relies on a chemical base as contrasted to conventional tillage but not drastically different than conventional cultivation methods. This system is being used by farmers worldwide and can have positive significant impact on the environment today and into the future.

US farmers each year, through land preparation for crops, move the equivalent amount of soil needed to build a super highway from New York to California. Manipulation of the soil creates a serious erosion problem on 50 per cent of the soils in the US, either from wind or water. Eroding soil has a very serious effect on the environment, including permanently reduced yield capability, and add to society’s cost in removing soil from streams, lakes, roads, and other public and privately owned areas.

When soils remain in place chemicals stay on the farm where needed. Relevant amounts of farm nutrients or pesticides move in runoff water except those attached to clay or silt soil particles.

No-tillage can reduce soil erosion from 50 mt/ha to 0.07 mt/ha according to a study conducted in Ohio, USA.

Rainfall infiltration is highly improved in no tillage farming, which is another resource important to agriculture remaining on the land where it falls.

Agriculture has not contributed to environmental problems to the extent many assume. Streams were sampled at the turn of the century in Kentucky and analysis made for nitrogen, potassium, phosphorus, calcium and other minor elements. Since the early sampling data farmers have made applications of these nutrients in fertilizers to soils for increased crop yields. A resampling was made in the mid-1970’s and levels of nutrients were identical to those recorded before chemical fertilizer was used extensively. The analyses of nutrients were in direct proportion to the inherent levels in the soils making up the drainage area of the streams prior to and after commercial fertilizers were widely used.

Much concern was expressed about increasing phosphorus levels in the northern US lakes, Agriculture was suspect in this increase until the major contributing source was found to be discharges from sewerage treatment and industrial plants. It is important to have a scientific base on environmental changes and contributing factors rather than emotional rhetoric.

No-tillage research has shown a rapid degrading of applied pesticides as compared to a soil that has been ploughed and dies several times, Properties that increase decomposition are generally light, microorganisms and organic matter. In no-tillage, less of the chemicals remain in the soil according to research reports from Ohio and Kentucky (data in Table 1).

Table 1: Response of oat and barley as a cover crop 124 days after chloro- 5-trazine application. Crop Injury

Slack, C.H. - University of Kentucky, 1973

No tillage offers an excellent opportunity to reduce the impact of chemicals but is not the sole method. Farmers and governmental education and regulatory agencies can, by working together, provide a vehicle to judiciously use chemicals in agricultural production.

Chemicals in most countries must be registered and labelled for use. Labelling is very restrictive and requires manufacturers to verify through exhaustive studies the compound’s impact on the environments

American farmers are required to be trained and then certified in the selection and application of pesticides in order to use the restricted materials (usually more toxic materials or higher concentrations of active ingredients). Training materials are developed by Colleges of Agriculture and training completed by Extension Agents with the State Department of Agriculture issuing the license to purchase restricted chemicals. Commercial applicators must complete more training and be re-licensed each year with intensive monitoring of applicator’s performance record.

Integrated Pest Management, a cooperative endeavour on the part of farmers, the US Department of Agriculture, and Colleges of Agriculture, is gaining popularity and use in the US as well as Australia and other countries.

The Colleges of Agriculture provide the technical base and supervision of the 1PM programme. A typical organisational structure starts with a State personnel of scientists from the disciplines of agronomy, horticulture, entomology, animal science, plant pathology and weed science to provide a consultation service organisation and programme management. Farmers join together to form an association to manage and fund each county 1PM programme. Costs are based on a per hectare charge sufficient to pay scouts who examine the field weekly to measure pest activity and a supervisor of scouts in larger commercial farming counties. Average fees vary by crop, but generally are in the $4-$6 per hectare range.

Field scouts examine individual farmer cooperator’s fields for any abnormalities of plant growth with major concern for nutritional deficiencies, disease, insect and weeds present or other conditions that may affect yields. These reports are installed in the College of Agriculture computer to provide a data base for present and future research and extension programmes. The County Extension Agent reviews the field reports and determines the economic threshold of the pest and makes a recommendation on action the farmer may elect to follow. These recommendations indicate problems by fields or section of fields, where chemical application is needed and, if so, selection of chemical, rate, timing and method of application. In many instances the farmer is advised not to apply chemicals if the predicted crop damage is less than the cost of the applied chemicals

The major advantages of this programme include:

(i) relieving farmer from pressure of field inspection during peak time demand periods;

(ii) reduction of chemical use;

(iii) timely information when chemical control is warranted;

(iv) final decision or action left with the farmer;

(v) collection of data base to evaluate controls, predict pest development and monitor trends in pest control.

Several States now report 5-10 per cent of. crop acreage presently involved in an IPM programme.

A definite trend towards biological control is developing worldwide through plant breeding, induced sterility, introduction of parasitic organisms as an alternative approach to replace chemicals in the production system. All systems will be needed to produce food and fibre demands while protecting the land resource available to man throughout the world.