For a variety of reasons (such as fossil fuel and farm machinery costs, soil compaction, PM-10 dust, etc) growers in California are looking for ways to reduce soil tillage without adversely impacting the growth and development of crops. The single biggest reason to till the soil is to provide a suitable environment for the seed to germinate. But for the widely spaced crops like cotton and corn, the seeds and seedlings occupy only a small proportion (4-8%) of the land area. Moreover, most of the soil tillage features (e.g., loose soil) are lost after the first irrigation due to soil wetting and drying. Hence, the natural question: how important is it to till the entire soil surface when the effective needed area is only 4-8%?

With the above question in mind, experiments on cotton and corn were conducted at U. C. Westside Research and Extension Center, Five Points and at UC Davis Agronomy Research Farm, respectively, for a period of three years continuously on the same piece of land. For site-specific tillage operations, a special tiller-planter was designed and fabricated at the Department of Biological and Agricultural Engineering at UC Davis. The tiller-planter incorporated mini roto-tillers, which tilled a 3-4” band of soil in front of the planter shoes/chisels. This also combined tillage and planting into a single and the only operation, resulting in a significant saving of time and resources.

The three years of experimentation showed that there was no effect of site-specific tillage on cotton yields as compared to conventional tillage. But a small but significant increase in yield was seen in the second and third years of corn crop due to site-specific tillage, as compared to conventional tillage.

Results of these experiments (including pictures) will be shown and discussed in the poster.