comparison of a three-harrow two-way square plow with a three-harrow one-way moldboard plow

a one-way moldboard plow turns over soil in only one direction. problems created by this type of tillage in iran include compaction of boundary regions, decreased efficiency of irrigation and disruption of bed leveling, requiring the use of bed-leveling equipment every few years. to overcome these problems, the use of a two-way plow with two harrows which turns over the soil to both the left and right sides is recommended by specialists. however, the weight and expense of these two-way plows along with the limited power of tractors available in iran rules out this method for most farmers. the two-way three-harrow square plow was designed to solve the problems of conventional two-way plows. in this study, the performance of the two-way three-harrow square plow was compared to the conventional one-way three-harrow moldboard plow. the tests were conducted according to the rnam test code and the recommendations of smith et al. at the training and research farm of the abureyhan campus of the university of tehran. the results showed that the bulk density of the soil after tillage by the two-way plow is significantly lower than for the one-way plow and soil evenness created by the two-way plow is more desirable than for the one-way plow. the difference between plow uniformity was not significant for the two types of plow.  the mean soil clod diameters were 31.96 mm and 39.86 mm for the two-way and one-way plows, respectively. the draft and tractor wheel slippage of the two-way plow were significantly greater than for the one way plow. it was generally concluded that the performances of the square plow and one-way plow are similar, thus recommending the used of the two-way plow.