Effects of Crimping by Oggun Tractor-mounted Roller/crimper on Cover Crop Termination, Soil Strength, and Soil Moisture in Upland Cambodia

Abstract

Rolling/crimping technology for terminating cover crops is essential to ensure that the rolled plant residue benefits both soil and succeeding cash crops. Cambodia has also adopted this technology, but it is still at the initial stage due to limited rolling services. The objectives of this study were to compare different roller-crimpers with the Oggun-mounted USDA roller-crimper in terminating sunn hemp (Crotalaria juncea L.) and to determine their effects on soil strength and soil moisture. The experiment was conducted in Rattanak Mondul, Battambang province in the wet season of 2019, using a randomized complete block design with three treatments having four replicates, each of which was 14 m x 34 m and spaced 5 m. The treatments consisted of (i) a USDA roller-crimper, mounted on 19-hp Oggun tractor, (ii) a Cambodian made roller-crimper with elliptic bars, and (iii) a disc-plow, both pulled by a 75-hp tractor. Plant height and biomass before rolling; soil strength at 0-10 and 10-20 cm depths before and after rolling; field operations; and soil volumetric moisture content (VMC) evaluated on the day of rolling, and then one, two, and three weeks after rolling, along with termination rate were analyzed. The results show that the height and biomass of sunn hemp were not significantly different among the treatments, being 164 cm and 2.57 t ha^-1. In Oggun crimping, speed and field efficiency were lowest, being 3.5 km h^-1 and 0.8 ha h^-1, but fuel use was highest. Under plow-based management, soil compaction was slightly higher and termination rate was more efficient, when compared to other treatments. Significant difference was not observed for VMC between the equipment used. However, crimping can be beneficial for cover crop termination, compared with disking that may have long-term effects on the soil.