Long-term effects of compost amendments and brassica green manures in potato cropping systems on soil and crop health and productivity

Authors: Larkin, Robert - Bob

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2022
Publication Date: 11/10/2022
Citation: Larkin, R.P. 2022. Long-term effects of compost amendments and brassica green manures in potato cropping systems on soil and crop health and productivity. Agronomy Journal. https://doi.org/10.3390/agronomy12112804.
DOI: https://doi.org/10.3390/agronomy12112804

Interpretive Summary: Current potato production practices can lead to degradation of soil health and fertility as well as declining yields and increased losses to soilborne diseases. Beneficial soil and crop management practices, such as longer rotations, cover crops and green manures, organic amendments, and reduced tillage, may improve soil and crop health and productivity when incorporated into cropping systems. Long-term trials are needed to assess the full impacts and effects of these systems. In field trials originally established in 2004, three different 3-yr potato cropping systems focused on management goals of soil conservation (SC), soil improvement (SI), and disease suppression (DS) were evaluated and compared to a standard 2-yr rotation (SQ) and a non-rotation control (PP). After 15 years and results compiled over a four-year period (2015-2018), The SI system (with a history of compost amendments) increased potato yields by 26 to 59% over standard rotations and improved various soil health properties, and the SI system continued to provide these benefits several years after amendments were ceased. The DS system, which included a disease-suppressive green manure rotation crop, also improved yield and other soil properties, as well as reduced potato diseases, whereas the nonrotation PP system resulted in notable of soil properties and yield over time. These results demonstrate that soil health management practices can be effectively incorporated into viable potato cropping systems to improve soil properties and crop health, and may enhance long-term sustainability. This research is useful for scientists, extension personnel, growers, and consumers, providing information on the development of improved cropping systems that enhance potato production and sustainability.

Technical Abstract: Beneficial soil and crop management practices, such as longer rotations, cover crops and green manures, organic amendments, and reduced tillage, may improve soil and crop health and productivity when incorporated into cropping systems. Long-term trials are needed to assess the full impacts and effects of these systems. In field trials originally established in 2004, three different 3-yr potato cropping systems focused on management goals of soil conservation (SC), soil improvement (SI), and disease suppression (DS) were evaluated and compared to a standard 2-yr rotation (SQ) and a non-rotation control (PP). After 15 years and results compiled over a four-year period (2015-2018), the SI system (with history of compost amendments) increased total and marketable tuber yield by 26 to 36% relative to the standard SQ system and 36 to 59% greater than PP. SI also improved soil properties such as organic matter and soil water content, nutritional characteristics, and microbial activity compared to the other systems. SI system continued to provide these improvements several years after compost amendments ended, indicating the long-term benefits. The DS system, which included a disease-suppressive green manure rotation crop and fall cover crops, also improved yield (by 16-20%), had higher OM content (by 12%), and increased microbial activity (by 22%) relative to SQ, as well as reducing the soilborne tuber diseases black scurf and common scab by 10-30%. The nonrotation PP system resulted in notable degradation of soil properties and yield over time. These results demonstrate that soil health management practices can be effectively incorporated into viable potato cropping systems to improve soil properties and crop health, and may enhance long-term sustainability.