Soil Biological Response to Integration of Cover Crops and Nitrogen Rates in a Conservation Tillage Corn Production System

Abstract

Core Ideas Use of N‐fertilizers decreased AMF populations and P, Ca, and Mg concentrations. Conservation tillage and cover crops increased C, N, and S cycling enzymes. Grass and brassica cover crops increased microbial populations compared to legumes. Agricultural production in the US Mid‐South has relied on frequent tillage and synthetic fertilizers decreasing soil health and system sustainability. Conservation tillage and cover crops can fill a vital role in reducing soil erosion while improving ecosystem functions. Seven cover crop blocks, including four legumes (berseem clover [Trifolium alexandrinum], crimson clover [Trifolium incarnatum L.], winter pea [Pisium sativum L.], and hairy vetch [Vicia villosa Roth], three grass & brassica (cereal rye [Secale cereale], forage radish [Raphanus sativus var. longipinnatus], and a cereal rye–forage radish mix), and one fallow control were established in northeast Louisiana to examine the influence of cover crop and urea fertilizer application rates (0, 235, 268, 302 kg N ha−1) on corn production and soil health under conservation tillage. Soil health indicators were measured each year following corn harvest and cover crop termination. The combination of cover crops and conservation tillage increased C and N enzyme activity over the 2 yr while arylsulfatase increased in the spring following cover crop termination only. Relative abundance of saprophytic fungi tended to be higher in legume plots compared to grass & brassica treatments. Overall, the application of N fertilizer at rates of 235 kg N ha−1 or higher decreased populations of AMF and concentrations of P, K, Ca, and Mg, but increased populations of Gram‐positive bacteria. The use of grass & brassica cover crops promoted K, S, Ca, and Mg availability, and supported greater abundance of total FAMEs and all FAME biomarkers except for saprophytic fungi.

Cover cropping and conservation tillage improve soil health in the southeastern United States

“…This reduction of soil nitrate and extractable P by the cover crop was only a temporary nutrient sequestration, as it was followed by organic release through mineralization for subsequent crop uptake after cover crop termination. On a site in the Southern Mississippi Alluvium MLRA, planting of several different legume cover crops [berseem clover ( Trifolium alexandrinum L.), crimson clover, winter pea ( Pisum sativum L.), and hairy vetch] for 2 yr resulted in significantly greater Mehlich‐III‐extractable P (35 vs. 32 mg kg −1 ) in the surface 10‐cm depth than with grass/brassica cover crops [rye, forage radish ( Raphanus sativus L.), and rye + forage radish], but lower K (145 vs. 155 mg kg −1 ), S (8.5 vs. 10.3 mg kg −1 ), Ca (1,043 vs. 1,107 mg kg −1 ), and Mg (172 vs. 179 mg kg −1 ) (Sanchez et al., 2019). Control plots without cover crops were often between these values.…”

Humic acid and nitrogen dose application in corn crop under alkaline soil conditions

“…There is a lot of studies reporting the benefits of N fertilization in different cereal crops such as corn (Ichami et al, 2019), wheat (Omara et al, 2020), and rice (Tatsumi et al, 2019). The optimum amount of N required for best cereal production depends on many factors, including soil type, indigenous nutrient concentration in the soil, weather conditions, and others (Sanchez et al, 2019). Therefore, studies aiming at determining the best N management practices related to N doses combined with HA application should be performed under different soil and weather conditions.…”

On-farm assessment of cover cropping effects on soil C and N pools, enzyme activities, and microbial community structure

“…CCs are helpful in altering soil microbial and enzyme activities (Frasier et al , 2016; Sanchez et al , 2019b). The activity of soil enzymes can be characterized and reflect the microorganism activity and soil quality condition (Benintende et al , 2008; Das and Varma, 2010).…”