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HomeMy WebLinkAboutThe Lucknow Sentinel, 1986-11-26, Page 45Soil Erosion: A concern for everyone The problem of soil erosion - the Ross of soil resources - has been a concern for farmers for many years. ,"gut how much does the non -farmer know about this growing problem? Not enough? This was the sentiment expressed by Senator erbert O. Sparrow, former chairman of the task force on soil erosion, at Soil Conservation Day held in August of this year. Sparrow noted that unless we undertake a concerted effort to combat the effects of soil erosion, we will see the end of Canadian agriculture in 30 years. Soil erosion also has serious en- vir • nmental effects, reducing water quality for wildlife and man. The fertile characteristics of the relatively thin topsoils was developed over thousands of years under the protective cover of forests. When pioneers arrived and removed the tree cover to create fields for growing food, the soil was left open to erosion by wind and water. The evidence of erosion is around us everyday in the form of brown, silted rivers; snow drifts discoloured by soil in winter and field corners filled with topsoil washed by rain. Unfortunately once soil is washed or blown away it cannot be replaced in the short term. In effect our supply of top- soil is limited to what exists today. Looking at land suitable for agriculture across Canada, there was an average of 15 inches of topsoil 100 years ago. Today an average of 6 to 7 inches re- mains. Erosion has a variety of consequences. The siltation of streams and rivers chokes aquatic life and destroys the spawning beds of fish. Soil particles carry pesticides and other substances that reduce the quality of water. On agricultural land the loss of topsoil means the loss of productivity. For consumers this will mean a jump in the cost of food in the future. The causes of erosion are many. The amount of rainfall, the type of soil, slope of fields, drainage and vegetative cover are all factors in erosion by water. Farm management techniques including tillage techniques that expose the soil to wind and water are also problems. ecause the Maitland Valley Watershed is dominated by agriculture, the M.V.C.A. has become involved in the problem of soil erosion. In 11985 the Joint Agricultural Soil and Water Conserytion Program was init- iated by a number of Conservation Authorities including the M.V.C.A. and the Ontario Ministry of Agricul- ture and Food. Vafeys & PeopPe - Fa!! 1906 - Page 5 The objectives of this program are to reduce soil erosion, improve soil and crop management practices, conserve the soil, improve water quality and maintain viable agricultural industry. The emphasis of the program is on tillage, crop rotation and field manage- ment practices. The benefits of soil conservation extend bey, nd the farm itself to the Maitland Valley Watershed as a wh:•?le. Program serves farmers In 1985 the Joint Agricultural Soil and Water Conservation Program was initiated by a number of Conservation Authorities and the Ontario Ministry of Agriculture and Food. The objectives of this program are to reduce soil erosion, improve soil and crop management practices, conserve the soil, improve water quality and maintain a viable agricultural industry. The emphasis of the program is on tillage, crop rotation and field manage- ment practices. Personnel with the Joint Agricultural Soil and Water Conservation program will: - provide you with access to conser- vation tillage equipment for plot exper- imentation on your farm - provide free technical assistance - prepare a soil and water conserva- tion plan for your farm - provide individual landowners with financial and technical assistance in the design of soil conservation structures continued on page 8 What is Conservation Tillage? The term, conservation tillage describes a popular method of improving on- farm soil and water conservation. However, no clear definition of "con- servation tillage" prevails. Some feel that any tillage system other than the conventional moldboard plow system is conservation tillage. Others assume that the use of a chisel plow in their tillage program every second or third year immediately classifies that system as conservation tillage. What is Conservation Tillage? Conservation tillage can probably be best defined as any system that meets or exceeds accepted residue cover standards and controls soil erosion by effectively reducing runoff. These standards are met by satisfying two main objectives: 1) retention of the previous crop's residue on or close to the surface as a protective mulch cover to improve infiltration and organic matter content, and 2) maintaining a rough, porous or ridged surface to induce infiltration and reduce erosion. Residue Must be Kept on the Soil Surface Crop residue kept at or near the soil surface protects the bare soil by dissipating the energy of falling rain, and by providing small channels and cracks to allow better water infiltration. Increasing the surface roughness provides small barriers to reduce the velocity of wind and water, and provides a source of organic matter that assists in improving the water holding capacity of the soil and ultim- ately its resistance to erosion. Research indicates that for a medium textured soil, 1000/lb./ac. (1,120 kg./ha.) of surface residue from the previous crop is required, after plant- ing, to have the .desired effect on the control of soil erosion by water on slopes ranging from 0 - 507o . As the potential for erosion increases (i.e. slopes increase or sandier soils) the recommended cover value increases. Examples: Findings from a study in LaSalle County Soil and Water Conservation District in Illinois reveals that on aver- age for every bushel (25 kg.) of grain corn harvested, 56 lbs. (25 kg.) of sur- face residue is produced. A yield of 120 bu./ac. (7,530 kg./ha.), therefore, results in a surface residue of approx- imately '6,720 lb./ac. (7,526 kg./ha.) prior to any tillage operation. Every tillage pass through until planting time the following spring will reduce this surface cover as shown in the following table. Tailor Your System Accordingly If 1,000 lb./ac. of surface residue is the goal for good erosion control one must next decide which tillage tools will achieve that goal on a particular farm and tailor the system accordingly. No one tillage machine, or set of lbs. of Residue Per Acre 6720 336 252 151 CONVENTIONAL TILLAGE % of Crop Residue Maintained by Tillage Equipment 507o Fall Moldboard Plow 75 %Overwinter Decomposition 6007o Spring Disc 80% Field Cultivate equals equals equals equals equals Residue Left lb./ac. 336 252 151 121 121 lb. ac. residue left on the soil surface prior to planting certainly is not enough to offer any appreciable protection against soil erosion. CONSERVATION TILLAGE 6720 X 50% Fall Mulch Tiller 3360 X 75% Overwinter Decomposition 2520 X 60% Spring Disc 1512 X 80% Field Cultivate equals equals equals equals 3360 2520 1512 1209 The remaining 1,209 lb./ac. of residue at soil surface before planting is suffici- ent to effectively control runoff and soil movement within tolerable limits. VINIIMMINIMONIMINIMIMMOIS machines, is best for all conditions. Soil textures, topography and moist- ure conditions all differ from farm to . farm. Likewise - crops change and weed problems vary. The type of farm operation may somewhat lirnit the choice of conservation tillage systems. In some instances, tillage alone cannot do a complete job in controlling soil erosion. Certain conditions may dictate that conservation tillage be, coupled with various other soil conser- vation measures such as: contouring, striperopping, rotations, grassed waterways, terracing, etc. Fully committed practicioners of conservation tillage emphasize that it is not just one machine, or one practice that makes it work - it is a system which they have modified and tailored to their specific farm conditions. Often, the system cannot be perfected in just one or two seasons. It may take' twice that time, or even more. Conservation tillage requires a full commitment on the part of the farm operator to make it work; both in terms of soil erosion control and economical crop production. Anyone - considering a conservation tillage system on their land is advised to talk to the real experts - the people who have made it work successfully. Area farmers and machinery dealers should be able to help you assess which machines are operating in conditions similar to your farm. Remember - conservation tillage, to be successful in the long term, requires an optimistic attitude. (Reprinted from Talk of the Thames, U.T.R.C.A., by Andy Graham, Senior Soil Conservation Advisor, O.M.A.F.)