Technology for Sustainable Agriculture

by Chet Townsend

Presented at a Forum on Sustainable Agriculture for

Florida Gulf Coast University

on April 7, 1998

The 1990 Farm Bill defined Sustainable Agriculture as "an integrated system of plant and animal production practices having a site-specific application that will, over the long term: satisfy human food and fiber needs; enhance environmental quality and the natural resource base upon which the agriculture economy depends; make the most use of nonrenewable resources and on-farm resources, and integrate, where appropriate, natural biological cycles and controls; sustain the economic viability of farm operations; and enhance the quality of life for farmers and ranchers, and society as a whole."

(Title XVI, Subtitle A, Sec. 1603)

Sustainable Agriculture is a way of farming that can be carried out for generations to come. This long-term approach to agriculture combines efficient production with the wise stewardship of the earth's resources. It is hoped that, over time, sustainable agriculture will do the following:

New technology in all areas has improved agricultural production, thus its sustainability. Today’s Agriculture is using best management practices (BMP’s), by targeting many of its applications, not broadcasting as was done in the past. New disease resistant hybrids, biological pest control, reduced pesticide use, cultural practices that reduce the incidence of pests and diseases, and better placement and reduced amounts of fertilizers are all being employed. Insect specific chemicals and biological insect controls are now being utilized, instead of broad-spectrum pesticides, that actually reduces the number of sprays needed along with costs. Micro-sprinkler water is now being applied directly to the roots, not overhead or flooding of the entire block as was done in the past. Agriculture manages land for both agriculture and wildlife. In many SW Florida citrus groves, water retention areas and woodland corridors allow animals and birds to flourish.

In citrus, technology has helped growers in many areas to reduce costs and improve production. Growers use disease resistant varieties where possible. Research and biotechnology have given growers new plant varieties that produce more and require fewer inputs.

IPM or integrated pest management is utilized in our production programs and have greatly reduced the applications of pesticides and the costs associated with sprays. For fruit that is processed into juice, only one or two sprays per year are applied to prevent fungal diseases that affect leaves. Most insects and diseases that cause fruit blemishes are ignored because outside appearance of fruit does not affect juice quality. However, healthy leaves are required to produce an economical crop. For fruit that is sold fresh and has to look its best before consumers will purchase it, IPM is employed with pest population levels monitored carefully. Sprays are only applied when an economical threshold is reached. Many insect pests today are controlled by biological control. When chemical pesticides are used, only those specific to the pest are used rather than using a broad spectrum pesticide, as was done in the past, that would also kill the beneficial insects. With the old broad spectrum pesticides, you would actually have to spray more often for your worst insect pests, because you would kill off the natural predators of that pest. Now we do not ever spray for many of those pests that our grandfathers did.

Fertilizers are often placed directly to the root zone using under-tree booms and/or through irrigation systems with computer control. Herbicides are used under the tree to control weeds that compete for water and fertilizer, thus reducing crop yield. Irrigation is only applied when the root zone moisture is depleted to a critical level. Much of the drainage water is retained onsite, thus recharging the aquifer. The water that does go off-site is cleaned through retention reservoirs.

Precision Agriculture is now coming to citrus production. I am part of a working group of growers working with research scientists developing an expert system called DISC, Decision Information Systems for Citrus <>. It is a computer tool where disease models, on a CD-ROM will interact with localized weather data from the Internet and grower inputs to help predict if and when disease conditions will be great enough to warrant a spray application. Knowing under what moisture and temperature conditions favor certain fungus diseases, a model, with real time weather data from a nearby weather station, or a weather station located on your property, can automatically be imported into a model to predict the disease pressure and tell you whether it is economically feasible to spray.

DISC Pre-plant models will help citrus growers to determine which rootstocks and grafted scion varieties (the top producing plant part) are best suited for a particular soil on your property. These models will be based on GPS, Global Positioning Systems, using satellites and soil maps plus the knowledge of citrus scientists and growers. GPS-GIS, Global Positioning Systems, Graphical Information Systems, will help growers utilize Precision Agriculture by matching inputs based on actual yields of different portions on the field or grove. If the soils on a particular area only yield so much, you can cut back on fertilizers in that area, thus saving money and the leaching of excess fertilizer into the surface water. Where soils are low in organic matter, less herbicides can be applied. Equipment capable of varying applications of fertilizers and chemicals need to be developed with GPS systems and groves need to be mapped to identify the needs of specific areas. These have to be, and will be, cost beneficial to be able to utilize this new technology. Already, many growers use sprayers that turn nozzles off and on depending on tree size using special sensors. For a large tree, all of the nozzles are open. For a small tree, only the lower nozzles are activated. If there is a dead or missing tree, all of the nozzles are turned off. This alone has saved some growers in excess of 30% of spray material costs and has reduced the amount of chemicals being applied.

By using the best hybrids, specialized applications of chemical pesticides and fertilizers, maximum economical production per acre can be realized. Without these inputs, more acreage would need to be cleared and farmed in the future to be able to provide the world’s growing population with safe, high-quality, and affordable supply of food and fiber. The most environmentally friendly solution is to upgrade all of the existing acreage, not clear more land to simply accommodate a shift due to economic reasons. If regulations and other inputs keep increasing agriculture’s costs that can’t be passed on to the consumer in a market driven economy, American Agriculture won’t survive. American Agriculture needs sustainability so that Americans can rely on a safe domestic supply of food rather than relying on foreign imports which could affect our security if cut off and not be able to guarantee its safety. However, I believe that American agriculture will somehow overcome these issues and prevail.

Copyright© 1998 - 1999 by Chet Townsend. No part of this publication may be copied, reproduced, stored in a retrieval system, or transmitted in any form or by any means - electronic, mechanical, photocopying, recording or otherwise - without the express written permission of the author. To request permission, send e-mail to

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