Conservation Tillage

Conservation Tillage

The term conservation tillage applies  to agricultural tillage practices that keep at least 30% of the soil surface covered by plant residues. The effects of conservation tillage on soil properties and on the prevention of soil erosion are great. In this article we will discuss the effects on nutrient losses.

Studies around the world show that, compared to plowed fields with little residue cover, conservation tillage usually reduces the total amount of water running off the land surface, and reduces even more the load of the nutrients and sediments carried by that runoff.


When combined with cover crop, the reductions are greater still. There is some concern that fertilizers and organic wastes applied to conservation tillage fields are not incorporated into the soil and are therefore more likely to be washed away. In most situations, the less soil surface is disturbed by the tillage, even when manure or sewage sludge is spread on it, the smaller are the losses of nutrients in surface runoff. The nutrient losses from an untilled field tend to be mostly dissolved in the water rather than attached to the sediments, while reverse is the true for tilled land. Because the large sediment associated nutrient losses, the total nutrient loss in surface runoff from conventionally tilled land generally is far greater than that from land where no-till or conservation tillage methods are used.

Conservation Tillage - Soil Erosion

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On the other hand, the loss of nutrients by leaching may be somewhat greater from land in conservation tillage systems than from land where conventional tillage is practiced. In conservation tillage systems, a higher percentage of the precipitation or irrigation water infiltrates into the soil, where it may carry nutrients downward. However over time many no-till soil develop large macropores that are open to soil surface.

Soil Conservation - Soil Science

Rain or irrigation water may move down rapidly through these macropores, with the result that nutrients held in the finer pores of the soil matrix are bypassed and do not leach into the lower horizons. In such situations, nutrient leaching may actually be less where conservation tillage is used.