Abstract
Supplying adequate amounts of soil N for plant growth during the growing season and across large agricultural fields is a challenge for conservational agricultural systems with cover crops. Knowledge about cover crop effects on N comes mostly from small, flat research plots and performance of cover crops across topographically diverse agricultural land is poorly understood. Our objective was to assess effects of both leguminous (red clover) and non-leguminous (winter rye) cover crops on potentially mineralizable N (PMN) and levels across a topographically diverse landscape. We studied conventional, low-input, and organic managements in corn-soybean-wheat rotation. The rotations of low-input and organic managements included rye and red clover cover crops. The managements were implemented in twenty large undulating fields in Southwest Michigan starting from 2006. The data collection and analysis were conducted during three growing seasons of 2011, 2012 and 2013. Observational micro-plots with and without cover crops were laid within each field on three contrasting topographical positions of depression, slope and summit. Soil samples were collected 4–5 times during each growing season and analyzed for and PMN. The results showed that all three managements were similar in their temporal and spatial distributions of NO3 —N. Red clover cover crop increased by 35% on depression, 20% on slope and 32% on summit positions. Rye cover crop had a significant 15% negative effect on in topographical depressions but not in slope and summit positions. The magnitude of the cover crop effects on soil mineral nitrogen across topographically diverse fields was associated with the amount of cover crop growth and residue production. The results emphasize the potential environmental and economic benefits that can be generated by implementing site-specific topography-driven cover crop management in row-crop agricultural systems.
Highlights
Nitrogen (N) is arguably the most important element for successful agricultural production and its adequate supply to plants is the key component of high yields
The regression analysis showed a significant relationship of soil organic nitrogen (SON) with NOÀ3 ÀN and potentially mineralizable N (PMN) under all three managements (p
The main two hypotheses of our study were (i) that the magnitudes of the effects from cover crops on soil PMN and NOÀ3 ÀN vary across topographical gradients, and (ii) that the amounts of biomass produced by cover crops are one of the drivers for the size of the cover crop effects
Summary
Nitrogen (N) is arguably the most important element for successful agricultural production and its adequate supply to plants is the key component of high yields. Keeping plant available soil N at an adequate level across large agricultural fields during the growing season can be a challenge for agricultural management systems. The two forms of soil mineral N absorbed by most plants are nitrate (NOÀ3 ÀN) and ammonium (NHþ4 ÀN) [2]. In wellaerated soils during the growing season NOÀ3 ÀN becomes the main form of N available for crops as microbial activity quickly transforms NHþ4 ÀN into NOÀ3 ÀN [3]. Proper agricultural management needs to consider both site-specific variations as well as temporal patterns in soil NOÀ3 ÀN to supply optimum amounts from both organic and mineral sources
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
