Soybean Yield Response to Soil Properties.

The physical and chemical properties of a soil play a big part in the plant’s ability to extract water and nutrients. Therefore, understanding the relationship between plant growth and these properties is important. We assessed the relationship between yield and soil properties and nutrients measured at 0 to 60 cm depth in a corn and soybean field. The experiment was conducted on a 10 acre field at Lincoln University’s Freeman farm. The soil of the experimental site was a Waldrom silty clay. Twenty four soybean and 24 corn plots were established in a randomized complete block design with three replications. Twelve of the soybean plots were tilled (CT) while the others were untilled (NT). The size of each plot was 40ft x 70ft. Soybean of the variety “morsoy” was planted in June and harvested in November 2011. Soil samples were taken in July 2011 at 0-10 cm, 10-20 cm, 20-40 cm and 40-60 cm depths and sent to a commercial laboratory for analyses. At the end of growing season, 4m² of each soybean plot was harvested and grain yield for each plot was calculated. Results showed that in magnitude, NT (99.85 g/m²) had higher yield as compared to CT (90.02g/m²) even though there was no statistically significant difference. Soybean yield could not be correlated with soil  properties, except pH at 40-60 cm depth. However, soybean yield was significantly correlated with nutrients such as K and P (p=0.0001. r=0.74) in 0-10 cm; but with only K in 20-40 cm. Most of the correlations were found in 10-20 cm depth where soybean yield was significantly correlated with Mg (p=0.0002. r=0.68), Na, Zn and Cu. The strong correlation between yield and P and Mg is understandable as these two nutrients are involved in the process of photosynthesis.