Date of Graduation

5-2021

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor

Trenton Roberts

Committee Member

Edward Gbur

Second Committee Member

Jeremy Ross

Third Committee Member

Kristofor Brye

Keywords

soybeans, soil health, crop management, crop production, winter practice, biomass production, blue lupin

Abstract

Cover crops have the potential to provide many benefits including weed suppression, erosion control, and improvements to soil quality. These benefits can be affected by species, biomass accumulation, and management practices. Although large amounts of biomass are good for maximizing benefits, it can result in problems for establishing the subsequent crop. Soybean [Glycine max (L.) Merr.] accounts for over 50% of Arkansas crop hectares annually; therefore, understanding the effect that a cover crop can have on the following soybean crop is crucial to the successful implementation of cover crops within the state. A study was established to evaluate winter cover crops as an alternative to traditional Arkansas practices, such as winter fallow, as well as winter wheat (Triticum aestivum L.) soybean double-crop system, and the effect each cropping system has on soybean yield and partial returns. Additionally, a goal of this study was to assess a variety of cover crop species and blends as well as their effect on aboveground biomass accumulation, nutrient uptake, and stand establishment of the following soybean crop. Soil organic matter (SOM) and pH were also used to evaluate overall soil health following three full rotations of each winter treatment. Results of the study show that winter cover crops do not affect the following soybean crop establishment, but had a positive influence on soybean yield and partial returns in a no-tillage system. Except for blue lupin (Lupinus angustifolius), each cover crop treatment proved to be an equally viable alternative to a traditional double-crop system and more profitable than a winter fallow system. Cover crops not only have an immediate impact of increasing soybean yield, but cover crops also have the potential to provide long-term benefits. Previous research has shown that increased biomass production typically increases SOM and results of this study indicate that cover crop treatments produced up to four times as much aboveground biomass compared to a winter fallow management strategy. Treatments that produced the most biomass also accumulated the most aboveground nutrient contents for the macronutrients nitrogen (N), phosphorus (P), and potassium (K). There were no differences in soil health calculations, but each treatment received a “good” soil health score. Our results indicate that winter cover crops provide a promising alternative to the winter wheat soybean double-crop system and winter fallow management program and with continuous management, soil quality can be improved.

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