Date of Award

4-9-2021

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Department of Agriculture

First Advisor

Nicholas J Heller

Abstract

Intercropping is the practice of growing multiple crops together in the same field. This is not commonly implemented in Midwest agriculture - instead, current monoculture practices have garnered attention because of the negative environmental impacts of monoculture farming. For this study, corn and soybean were intercropped in a production agriculture setting to investigate the benefits to the producer and the environment. Intercropping corn and soybean crops may reduce the need for added nitrogen (N) fertilizer, saving money on inputs and potential loss of N from the farm to the environment. Soybeans within the system may utilize less of the soil N leaving more N, available for the corn crops. Soybean plants are legumes and form a symbiotic relationship with bacteria the soil, Bradyrhizobium japonicum, which allows the soybean plant to fix plant-unavailable N into a plant-available form. Therefore, corn plants within the intercropping system would require little, if any, synthetic N fertilizers.An intercropping system may decrease the loss of N associated with greenhouse gases and acid rain components. The loss of N through leaching and denitrification are seen in monoculture practices where N fertilizer is used. The cause of the negative environmental impacts is from the over application of nutrients that are lost from the soil profile. The macronutrients which crops require in large amounts include nitrogen (N), phosphorous (P), and potassium (K). N, P, and K are being lost in large amounts increasing the creation of laws in many areas, like the Chesapeake Bay and the Lake Eerie watershed, are limiting how much and when fertilization can occur. The proposed intercropping system could increase farmer profit without any additional N fertilizer applied. This study compares monoculture and intercropped systems of corn and soybean. All plots are treated the same for fertility in that no supplemental macronutrients were applied. The monoculture treatments were 38-cm corn (narrow-row corn), 38-cm soybean (narrow-row soybean), 76-cm corn (wide-row corn), and 76-cm soybean (wide-row soybean). Populations were constant for the monocropping treatments: 83,980 corn plants ha-1 (34,000 plants ac-1) and 345,000 soybean plants ha-1 (140,000 plants ac-1). These four monoculture treatments were compared to two intercropping treatments, intercropped corn and soybean with a corn population of 27,993 plants ha-1 (11,333 plants ac-1) and intercropped corn and soybean with a corn population of 55,985 plants ha-1 (22,666 plants ac-1). Since producers are constantly manipulating different cropping systems, this study took into consideration differences in the effect of row orientation and row spacing on yield. Thus, this study compares current monoculture production to intercropping to determine if intercropping could be profitable while requiring fewer environmentally-insensitive inputs. Throughout the study, various statistical analyses were conducted to evaluate if there were any differences between the six treatments. Results evaluating the impact of row orientation and row spacing on corn and soybean production showed that both row orientation and row spacing did not significantly influence corn and soybean productivity. Comparing corn leaf tissue, corn intercropped with soybean contained a significantly greater N concentration within the plant tissue than monoculture corn (p = 0.0006). This difference was visually observed during the 2020 growing season. Further, the results showed that intercropped corn and soybean produced a greater weight of seed per plant than any of the monoculture treatments. Profitability of the monoculture and intercropped treatments was further evaluated to compare the two cropping systems. Two different analyses were conducted, comparing the different prices of corn and soybean at a set market price, and then comparing the different treatments at a range of potential prices. On 19 October 2020 the grain was sold at Prairie Central Co-operative in Lexington, IL. The price received for soybean was $10.24 bu-1 , and corn was $3.79 bu-1 . The intercropping profit was significantly greater than all the monoculture treatments. Since grain prices vary significantly from year to year, different ranges of prices were further evaluated using historical prices from the past 10 years. This resulted in a price range of $3.00 to $6.00 for corn prices and $8.00 to $14.00 for soybean prices. Different price combinations were evaluated and showed that the intercropping treatment was more profitable than the monoculture treatments at most combinations of corn and soybean prices. Further, the profitability of intercropping compared favorably to traditional monocrop corn grown in the Midwest using N fertilizer. Results of this study show that intercropped corn and soybean may be more profitable and benefit the environment from reduced inputs of N fertilizer.

Comments

Imported from Huffman_ilstu_0092N_11939.pdf

DOI

https://doi.org/10.30707/ETD2021.20210719070603177144.69

Page Count

103

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