Identifying the best tillage system to maintain soil properties and crop yields after Conservation Reserve Program grassland conversion

Authors: Klopp, Hans; BLANCO-CANQUI, HUMBERTO - University Of Nebraska; CREECH, CODY - University Of Nebraska; EASTERLY, AMANDA - University Of Nebraska

Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/19/2024
Publication Date: 3/1/2024
Citation: Klopp, H.W., Blanco-Canqui, H., Creech, C.F., Easterly, A.C. 2024. Identifying the best tillage system to maintain soil properties and crop yields after Conservation Reserve Program grassland conversion. Soil & Tillage Research. 239. Article 106060. https://doi.org/10.1016/j.still.2024.106060.
DOI: https://doi.org/10.1016/j.still.2024.106060

Interpretive Summary: Conservation Reserve Program (CRP) is a program available from the Farm Service Agency-USDA that provides a financial incentive to transition croplands to perennial vegetation for a contracted duration. When the contract expires, farmers are faced with the choice of whether to re-enroll their land in CRP or return the land to cropping. Returning the land to cropping may undo some of the potential benefits provided to the soil from perennial vegetation during a CRP contract. However, there are conflicting data regarding changes in soil health properties when cropping is resumed. Therefore, the objectives of this study by scientists from ARS (Bushland, Texas) and the University of Nebraska were to determine what tillage practice best maintained soil chemical and physical properties and produced the highest crop yields when CRP was returned to cropland. The experiment was conducted on a winter wheat-corn-fallow rotation in the Nebraska Panhandle for one rotation (3 years). Tillage practices included no-till (NT), disk-sweep (RT), plow-sweep (PS) and deep plow-sweep (DPS). In this study tillage practice did not affect winter wheat or corn grain yields. Stability of soil structure and availability of soil water to plants near surface was reduced when CRP was returned to cropland regardless of tillage practice. However, NT and RT did not cause as large of a reduction in soil structure. These results demonstrated that using NT or RT when returning CRP to cropland can maintain some soil properties to similar levels as at the end of CRP.

Technical Abstract: The Conservation Reserve Program (CRP) is a government program that provides financial incentives to transition marginal croplands to permanent grass cover as a soil and water conservation technique. Few studies have analyzed the effects of tillage intensity when converting CRP back to cropland on soil properties. Our objectives were to 1) determine how converting CRP to cropland under different tillage practices after three years affects soil Carbon (C) stocks, physical and chemical properties, and winter wheat (Triticum aestivium L.) and corn (Zea mays L.) grain yields. In addition, we reviewed the literature of published studies on the topic to compare previous results against our findings. This study was conducted in Sidney, Nebraska, USA, on CRP that was converted to production farmland through four tillage practices no-till (NT), disk-sweep (RT), plow-sweep (PS), deep plow-sweep (DPS) in 2017, and planted to a wheat-corn-fallow rotation. We measured soil C, chemical and physical properties on samples collected in fall of 2020, and crop yields. Total and organic C stock in the top 60 cm was not affected when CRP was converted to cropland although organic C stock was reduced by 6% in PS and 15% in DPS compared to CRP in the 0-10 cm depth. Tillage practice did not affect grain yields in our study but had inconsistent effects in previous literature. Compared to CRP wet aggregate stability (0-10 cm) was reduced by 41% in RT, 51% in PS, and 58% in DPS, dry aggregate stability was reduced (0-5 cm) by 66% in NT, 71% in RS, 74% in PS and 77% in DPS, and plant available water (5-10 cm) was reduced by 45% in NT, 50% in RT, 39% in PS and 43% in DPS treatment. However cumulative infiltration rate after 180 minutes and bulk density was not affected by any of the treatments. The use of RT or NT when converting CRP to cropland caused the fewest negative impacts on soil quality when CRP was converted to cropland in our study and in previous studies from the literature. Minimizing soil disturbance by tillage when converting CRP to cropland can maintain some of the soil properties to a similar level of CRP three years after it is returned to cropland.