Comparison of Soy Protein Based and Commercially Available Seed Lubricants for Seed Flowability in Row Crop Planters

Abstract

Abstract. Seed lubricants play a crucial role in proper seed singulation by ensuring a smooth flow of the seeds through the metering unit. However, the harmful chemicals inadvertently expelled along with the air during the seed metering process have raised concerns regarding the negative effects of available lubricant to the environment. An alternative has been developed from soy protein, however, no knowledge exists regarding its suitability as a potential seed lubricant. Therefore, the objectives of this study was (1) to assess seed flowability by quantifying seed singulation for both corn () and soybean () crops, and (2) to perform a simple cost analysis to determine the cost of usage of each seed lubricant. To address these objectives, two Horsch planter row units were used to run simulated planting scenarios in the laboratory. One row unit was equipped with a seed tube sensor to record seed tube seed count and time interval while the other one was fitted with an encoder to record seed meter motor rpm. These data were used to quantify percentage seed singulation, skips/misses, and multiples. Treatment factors were seed size with three levels: small, medium, large and seed lubricant with four levels: talc, fluency agent; soy protein based, and fourth being no lubricant. Row unit was programmed to plant seeds at 7.2 kph (5 mph) simulated ground speed with a target population of 89,000 seeds/ha for corn and 370,000 seeds/ha for soybean. Each test was replicated three times in a completely randomized design. For corn, result suggests that large seeds of different shapes showed greater singulation irrespective of type of seed lubricant. For soybeans, results suggest that both seed lubricant and seed size could potentially affect seed flowability. Medium size soybeans exhibited greater singulation for all four levels of seed lubricants while Fluency Agent and soy protein resulted in greater singulation along with fewer skips and multiples. A cost analysis shows that usage cost of soy protein as seed lubricant is 63% less expensive as compared to Fluency Agent although slightly expensive by 44% compared to talc. In summary, soy protein could be an alternative seed lubricant for row crop planters in providing equivalent or better seed flowability, cost-effectiveness and environmental stewardship. Keywords: Seed flowability, Row crop planter, Singulation, Seed lubricant, Soy protein.