Corn (Zea mays L.) grain is a major commodity crop in Illinois and its production largely relies on timely application of nitrogen (N) fertilizers. Currently, growers in Illinois and other neighboring states in the U.S. Midwest use the maximum return to N (MRTN) decision support system to predict corn N requirements. However, the current tool does not factor in implications of integrating cover crops into the rotation, which has recently gained attention among growers due to several ecosystem services associated with cover cropping. A two-year field trail was conducted at the Agronomy Research Center in Carbondale, IL in 2018 and 2019 to evaluate whether split N application affects nitrogen use efficiency (NUE) of corn with and without a wheat (Triticum aestivum L.) cover crop. A randomized complete block design with split plot arrangements and four replicates was used. Main plots were cover crop treatments (no cover crop (control) compared to a wheat cover crop) and subplots were N timing applications to the corn: (1) 168 kg N ha−1 at planting; (2) 56 kg N ha−1 at planting + 112 kg N ha−1 at sidedress; (3) 112 kg N ha−1 at planting + 56 kg N ha−1 at sidedress; and (4) 168 kg N ha−1 at sidedress along with a zero-N control as check plot. Corn yield was higher in 2018 than 2019 reflecting more timely precipitation in that year. In 2018, grain yield declined by 12.6% following the wheat cover crop compared to no cover crop control, indicating a yield penalty when corn was preceded with a wheat cover crop. In 2018, a year with timely and sufficient rainfall, there were no yield differences among N treatments and N balances were near zero. In 2019, delaying the N application improved NUE and corn grain yield due to excessive rainfall early in the season reflecting on N losses which was confirmed by lower N balances in sidedressed treatments. Overall, our findings suggest including N credit for cereals in MRTN prediction model could help with improved N management in the Midwestern United States.
Growing winter cereal rye (Secale cereale) (WCR) has been identified as an effective in-field practice to reduce nitrate-N and phosphorus (P) losses to Upper Mississippi River Basin, USA. In the Midwestern USA, growers are reluctant to plant WCR especially prior to corn (Zea mays L.) due to N immobilization and establishment issues. Precision planting of WCR or ‘skipping the corn row’ (STCR) can minimize some issues associated with WCR ahead of corn while reducing cover crop seed costs. The objective of this study was to compare the effectiveness of ‘STCR’ vs normal planting of WCR at full seeding rate (NP) on WCR biomass, nutrient uptake and composition in three site-yrs (ARC2019, ARC2020, BRC2020). Our results indicated no differences in cover crop dry matter biomass production between the STCR (2.40 Mg ha−1) and NP (2.41 Mg ha−1) supported by similar normalized difference vegetative index and plant height for both treatments. Phosphorus, potassium (K), calcium (Ca) and magnesium (Mg) accumulation in aboveground biomass was only influenced by site-yr and both STCR and NP removed similar amount of P, K, Ca and Mg indicating STCR could be as effective as NP in accumulating nutrients. Aboveground carbon (C) content (1086.26 kg h−1 average over the two treatments) was similar between the two treatments and only influenced by site-yr differences. Lignin, lignin:N and C:N ratios were higher in STCR than NP in one out of three site-yrs (ARC2019) indicating greater chance of N immobilization when WCR was planted later than usual. Implementing STCR saved $8.4 ha−1 for growers and could incentivize growers to adopt this practice. Future research should evaluate corn response to STCR compared with NP and assess if soil quality declines by STCR practice over time.
<p>Dairy producers often apply manure to meet the nitrogen (N) needs of a corn (<em>Zea mays</em> L.) crop (N-based management). This can increase soil carbon (C) but leads to overapplication of phosphorus (P) and potassium (K) which could result in increased soil test P (STP) and K (STK) over time. One stategy used in manure management to achieve N requirement of a corn crop while reducing STP and STK buildup and increasing soil C is to move from a N&#8208;based applications of manure to a P&#8208;based (crop&#8208;removal) management with integrating winter cereal rye (<em>Secale cereale</em> L.; WCR) as double crop with corn silage and supplementing N need with inorganic fertilizer. A four-year trial was initiated in Breese, IL in 2019. The experimental design was a randomized complete block design with four replicates. Treatments were (1) corn silage with liquid UAN fertilizer; (2) P-based manure with no WRC; (3) N-based manure (liberal N credit) with no WCR; (4) N-based manure (conservative N credit) with no WCR; (5) P-based manure with WRC; (6) N-based manure (liberal N credit) with WCR; (7) N-based manure (conservative N credit) with WCR. We measured corn and rye yield, the N and P concentrations in the biomass, N and P removal and balances for the system, and soil test P. We also evaluated phospholipid fatty acids (PLFA), soil aggregate size distribution and stability, soil bulk density, soil &#946;-glucosidase (BG) enzyme, soil organic C and labile C (POXC) over a 90 cm soil profile. Our results indicated that integrating WCR with P-based manure rates maintains STP over time. High rate of manure (conservative N credit) and WCR resulted in increased soil C which was supported by higher fungi:bacteria ratio in the soil.</p>
<p>Agricultural soil&#160; management is the main source of nitrous oxide (N<sub>2</sub>O) emission, contributing 78% of total N<sub>2</sub>O emissions. Winter cereal cover crops (WCCCs) are recommended as the best in-field management practice to minimize nutrient loss to Illinois water and the Gulf of Mexico. WCCCs including wheat (Triticum aestivum L.) are often terminated 3-4 weeks prior to planting corn. Delaying termination increases nitrogen (N) uptake and decreases N leaching potential. Literature is scant on the effect of wheat termination (early vs. late or cover crop removal) on corn yield and N<sub>2</sub>O emission during corn growing season. The objective of the study includes evaluating effect of wheat termination management vs. a no-cover crop control on (I) corn leaf area index (LAI) and grain yield; (II) soil nitrate-N, ammonium-N, and total N dynamics; (III) soil volumetric water content (VWC) and temperature trends; (IV) soil N<sub>2</sub>O emission; and (V) yield-scaled N<sub>2</sub>O emissions. We found that Corn yield was higher in Fallow and explained by peak LAI values. Majority of N<sub>2</sub>O emissions occurred after N fertilization prior to corn V10 growth stage. Soil nitrate-N had its peak period after sidedressing N coinciding with peak N<sub>2</sub>O emissions for most of cover crop treatments. Yield-scaled N<sub>2</sub>O emission were lowest in the fallow in both years and varies across other cover crop treatments in 2020 and 2021 reflecting on lower N balances in that treatment. Average soil VWC prior to corn V10 growth stage explained 74% of soil N<sub>2</sub>O-N emissions indicating when N is supplied in high amount, soil VWC drives N<sub>2</sub>O-N emissions. Gram + bacteria was negatively related to cumulative N<sub>2</sub>O-N emissions.</p>
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