Cropping system, landscape position, and topsoil depth affect soil fertility and nutrient buffering

Authors: CONWAY, LANCE - University Of Missouri; Yost, Matt; Kitchen, Newell; Sudduth, Kenneth - Ken; Veum, Kristen

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2018
Publication Date: 3/22/2018
Citation: Conway, L.S., Yost, M.A., Kitchen, N.R., Sudduth, K.A., Veum, K.S. 2018. Cropping system, landscape position, and topsoil depth affect soil fertility and nutrient buffering. Soil Science Society of America Journal. 82(2):382-391. doi:10.2136/sssaj2017.08.0288.
DOI: https://doi.org/10.2136/sssaj2017.08.0288

Interpretive Summary: Within-field variability of soil properties and productivity has been exacerbated by decades of erosion on claypan soils throughout the Midwestern United States. Understanding how different crop management practices respond to this degradation across landscapes is vital to optimizing fertilizer inputs. Therefore, research was conducted to determine how the interactions of landscape position, cropping system, and topsoil depth affect soil fertility over time. The study was conducted from 2010 to 2016 near Centralia, MO on large plots that were established in 1991 and are included in the Central Mississippi River Basin site of the USDA Long-Term Agroecosystem Network. Results indicated that landscape position and cropping system affected all aspects of soil fertility. An extended annual grain crop rotation that included no-tillage and cover crops had lower soil test phosphorus and potassium, greater soil organic matter, and was less susceptible to change in soil test phosphorus than other annual grain cropping systems. Additionally, soil test phosphorus was more stable and soil test potassium was less stable across all cropping systems at deeper topsoil depths. These findings demonstrate that adjusting fertilizer rates based upon cropping system and topsoil depth could enhance fertilizer efficiency. This information will help producers and their consultants improve fertility management in conventional and conservation-based cropping systems across claypan soil landscapes.

Technical Abstract: Precise nutrient management across claypan soil landscapes requires an understanding of how diversity in management practices impacts soil properties and nutrient buffering. Therefore, a study was performed at the Central Mississippi River Basin site of the USDA Long-Term Agroecosystem Network from 2010 to 2016 to determine how depth to claypan (DTC), cropping system (CS), and landscape position (LP) affect soil properties with time, and whether accounting for these three factors could improve fertility management on claypan soils. Treatments consisted of five CS [MTCS, mulch till corn (Zea mays L.)-soybean (Glycine max {L.} Merr.); NTCS, no-till corn-soybean; NTCSW, no-till corn-soybean-wheat {Triticum aestivum L.}-cover crop; CCRP, cool season conservation reserve program; and HAY, cool and warm season hay] and three LP (summit, backslope, and footslope), each with distinct DTC. Landscape position and CS affected nearly all aspects of soil fertility. Soil test P (STP) was lowest on summits, pHs (salt pH) was generally greatest on footslopes, and soil test K (STK) and organic matter (OM) were greatest on backslopes. Lower STP and STK levels were observed in NTCSW when compared to MT- and NT-CS. However, the inclusion of wheat and cover crops in NTCSW maintained STP and increased OM. Soil test P, pHs, and OM were similar between CCRP and HAY, while STK in CCRP was greater at all LP. Lastly, deeper DTC caused greater P buffering (i.e., less change with fertilizer additions and/or crop removal) and less K buffering than shallower DTC. These results indicate that eroded sideslopes with shallow DTC likely need more or more frequent P and less K than other LP.