Cutting management and alfalfa stand age effects on organically grown corn grain yield and soil N availability

Abstract

Alfalfa is recommended as a rotational crop in corn production, due to its ability to contribute to soil nitrogen (N) and carbon (C) stocks through atmospheric N2fixation and above- and belowground biomass production. However, there is little information on how alfalfa management practices affect contributions to soil and subsequent corn crop yields, and research has not been targeted to organic systems. A study was conducted to determine the effects of alfalfa stand age, cutting frequency and biomass removal on soil C and N status and corn yields at three organically managed Minnesota locations. In one experiment, five cutting treatments were applied in nine environments: two, three and four cuts with biomass removal; three cuts with biomass remaining in place; and a no-cut control. In the other experiment, corn was planted following 1-, 2-, 3- or 4-year-old alfalfa stands and a no-alfalfa control. Yield was measured in the subsequent corn crop. In the cutting experiment, the two- and three-cut treatments with biomass removal reduced soil mineral N by 12.6 and 11.5%, respectively, compared with the control. Potentially mineralizable N (PMN) was not generally affected by cutting treatments. The three-cut no-removal increased potentially mineralizable C by 17% compared with the other treatments, but lowered soil total C in two environments, suggesting a priming effect in which addition of alfalfa biomass stimulated microbial mineralization of native soil C. Although both yields and soil mineral N tended to be higher in treatments where biomass remained in place, this advantage was small and inconsistent, indicating that farmers need not forgo hay harvest to obtain the rotational benefits of an alfalfa stand. The lack of overall correlation between corn grain yields and mineral and potentially mineralizable N suggests that alfalfa N contribution was not the driver of the yield increase in the no-removal treatments. Alfalfa stand age had inconsistent effects on fall-incorporated N and soil N and C parameters. Beyond the first year, increased alfalfa stand age did not increase soil mineral N or PMN. However, corn yield increased following older stands. Yields were 29, 77 and 90% higher following first-, second- and third-year alfalfa stands than the no-alfalfa control, respectively. This indicates that alfalfa may benefit succeeding corn through mechanisms other than N contribution, potentially including P solubilization and weed suppression. These effects have been less studied than N credits, but are of high value in organic cropping systems.

Improvement of Medicago sativa Crops Productivity by the Co-inoculation of Sinorhizobium meliloti–Actinobacteria Under Salt Stress

“…Also, it has been reported that a large part of their genome (~5–10%) is devoted to the production of secondary metabolites which help them to grow even in extreme conditions. Actinobacteria are widespread in aquatic and terrestrial habitats, including extreme habitats and hyper-arid desert soils [ 13 ]. This was clearly shown by the tolerance of these strains to abiotic stress, particularly aridity and salinity.…”

“…The integration of legumes into agricultural techniques, such as intercropping, cover crops and crop rotation can restore soil health by their ability to fix nitrogen in a symbiotic interaction with the rhizobia of the soil. Based on their ability to grow on soils low in nitrogen, they can be used effectively to improve saline soil fertility and contribute to the reintroduction of agriculture on these lands [ 13 ]. In this line, Sinorhizobium meliloti (strain 1021) and its symbiotic interaction with Medicago sativa is a widely recognized model system for studies of symbiosis and nitrogen fixation.…”

Uptake Dynamics of Ionic and Elemental Selenium Forms and Their Metabolism in Multiple-Harvested Alfalfa (Medicago sativa L.)

“…Moreover, its dense root system enriches the soil organic matter content, soil biological activity, provides physical protection against wind and water erosion also reduces soil erosion [ 5 ]. Alfalfa, a herbaceous perennial plant, can regrow from the buds located in the crown after dormant state caused by unfavorable growth conditions [ 6 ]. Green biomass of alfalfa can be harvested 3–7 times per vegetation season depending on the variety, temperature, and irrigation.…”

Nonchemical control of a perennial weed, Cirsium arvense, in arable cropping systems. A review

“…The introduction of pluriannual forage crops is particularly beneficial, as no additional specific intervention is necessary since repeated mowing is needed to harvest alfalfa and temporary grasslands. Moreover, these cropping practices have a positive impact on soil fertility (Fernandez et al 2017;Jarvis et al 2017) unlike other nonchemical control practices, especially mechanical interventions (Thomsen et al 2015;Melander et al 2016).…”