ELSEVIER Soil & Tillage Research 41 (1997) 165-167

Editorial

Tillage system impacts on environmental quality and soil biological parameters

W.A. Dick ’ School of Natural Resources, The Ohio State Unioersity, Wooster, OH, 446914096. USA

Abstract

“Soil Tillage for Crop Production and Protection for the Environment” was the theme of the 13th International Conference of the International Soil Tillage Research Organization (ISTRO). This conference was held in Aalborg, Denmark from 24 to 29 July 1994. Approximately 200 oral and poster papers relating to the conference’s theme were presented. As a follow-up to this meeting, the Secretary-General of ISTRO solicited papers by various conference delegates. These papers are collected into this issue of Soil & Tillage Research. The goal of this special issue is to stimulate further research and discussion of the impact of tillage on the quality of the environment as defined by water and atmospheric parameters and to focus on the role of tillage as it influences the biological component of soil.

Keywords: Conservation tillage: No-tillage; Soil biology; Crop diseases: Greenhouse gases; Crop rotation; N cycling; Cropping systems: Pesticides; Deforestation; Soil organic C; Soil structure; Soil macropore

Agriculture presumably began as a no-tillage system where a pointed stick was used to place seed directly into untilled soil. In many parts of the tropics, no-tillage is still a part of slash and burn agriculture. However, as humans developed a more systematic agriculture, cultivation of the soil became an accepted practice for preparation of a more suitable environment for plant growth. Pictures in ancient Egyptian tombs portray a farmer tilling his field using a plow and oxen prior to planting of the seed. Indeed tillage, as symbolized by the moldboard plow, became almost synonymous with agriculture.

Tillage systems have evolved over long time periods. A tillage system integrates

’ Tel.: + l-330-263-3877; fax: + I-330-263-3658; e-mail: dickS@osu.edu.

0167-1987/97/$17.00 Copyright 0 1997 Elsevier Science B.V. All rights reserved. PI/ SOl67-1987(96)01093-S

166 W.A. Dick/Soil & Tillage Research 41 (1997) 16.5-167

many soil and climatic factors that reflect the knowledge of the local farm population. Tillage systems that have evolved over time are often highly sustainable and, until recently, these tillage treatments were thought to represent the best and most dependable methods of crop husbandry.

The advantages of tillage are many. Tillage prepares an excellent seedbed. It is an excellent method for controlling weeds. Tillage loosens the soil so that it can be aerated, absorb water, and stimulate root growth. Tilling the soil buries the residue of old plants, including burying with them certain disease organisms and insects that might attack the new crop. Finally, tillage often enhances the effectiveness of fertilizer applied to the soil for improving crop growth.

One may wonder why anyone would even think of eliminating or reducing such firmly established tillage practices. Under some conditions, however, the elimination or reduction of tillage can make the farmer’s task easier and more profitable. Other disadvantages of tillage are that power and labor demands are high, particularly during the planting season which is often very short. Tillage also removes the residue of the previous crop from the soil surface, thereby increasing the susceptibility of the soil to erosion. This in turn reduces the agricultural potential, and sustainability, of the land. Bare soil is also likely to lose more water by evaporation and runoff than soil covered by plant residues so that the crop has less water for growth.

If less tillage is practiced, other methods must be used for control of weeds, insects, and diseases. Traditionally, tillage has performed the role of weed, disease, and insect control. To substitute for tillage, farmers are forced to use pesticides. If applied properly, pesticides generally pose little risk to the environment. Fertilizer practices must also be altered when we move to a less intensive tillage system. For example, no-tillage almost always requires application of fertilizer to the soil surface where it is most susceptible to being washed off by surface runoff of water during periods of intense precipitation. Tillage practices may also lead to conditions in the soil that increase movement of water downward through the soil profile. Finally, we are increasingly being made aware of the importance of tillage to impact carbon sequestration in the soil and the impact of tillage on the evolution of radiatively active atmospheric gases such as carbon dioxide and nitrous oxide. This interaction of tillage with soil biological factors, water and air is only poorly understood.

Tillage, or lack of tillage as is the case for the no-tillage agricultural production systems, is the one farming variable that most directly impacts our environment. It can greatly alter the soil physical, chemical, and biological properties leading to changes in crop productivity and the quality of the environment. From 24 to 29 July 1994 the 13th International Conference of the International Soil Tillage Research Organization (ISTRO) was held in Aalborg, Denmark. The theme of this conference was “Soil Tillage for Crop Production and Protection of the Environment”. Approximately 200 papers related to this theme were presented either orally or as posters.

As a follow-up to this meeting, the Secretary-General of ISTRO solicited papers by various conference delegates to further address the theme of how tillage interacts to affect the soil biology and the quality of the environment. These papers are collected into this issue of Soil & Tillage Research. Seven papers dealing with the interaction of tillage and the biology of the soil or the interaction of tillage and the quality of the

W.A. Dick/Soil & Tillage Research 41 (19971 165-167 167

environment are presented. These papers represent tillage research conducted in North America, Europe, and Africa. The goal of this special issue is to stimulate further research and discussion on the impact of tillage to affect the quality of the environment as defined by water and atmospheric parameters and to focus on the role of tillage as it influences the biological component of soil.