Effects of Different Management Methods for Sunn-Hemp Cover Crop on Corn Production in A No-Till System in Cambodia

Abstract. Conservation agriculture (CA) is gaining popularity in Cambodia to sustain soil fertility, productivity, and profits. However, the adoption remains slow due to the low engagement so far of local services into CA machinery and technology. Therefore, this paper aimed to compare different no-till seeders for corn sowing and to determine their effects on growth and yield. The experiment was conducted in Rattanak Mondul District, Battambang Province, in the wet season of 2019, using a split-plot design with plot type as main plots, arranged in a randomized complete block design, and seeder type as sub-plots. Sunn hemp (Crotalaria Juncea) was grown as cover crop prior to corn 74 days. Then, three main treatments were implemented with (i) sunn hemp used as green manure crop and buried through tillage, (ii) sunn hemp crimped by Cambodia made crimper, and (iii) sunn hemp crimped by USDA crimper. Each main plot was 14 m x 34 m and was subdivided lengthwise with 4.0-m buffers for operations of two different seeders, namely one-row Morrison seeder mounted on 19-hp Oggun tractor and four-row Brazilian seeder mounted on 75-hp John Deere tractor. The results show that using Brazilian seeder saved nearly 50% of seed and 80% of time. Plant height and diameter, and corn yield, were also significantly greater, when compared to the Morrison seeder. Unlike disked plots, crimped plots had larger fruit size and weight. VMC was significantly affected by plot type. The study demonstrates that using no-till planters in CA plots may lead to higher corn yield, but that small-scale planters may not be suitable for big cultivation areas.