Integrating cover crops into farming systems may contribute to meeting N demands of succeeding crops and therefore decrease fertilization and environmental concerns. To study the trend of released N in buried (BR) and surface residues (SR) of three different cover crops a 2‐yr field experiment was conducted in a randomized complete block design on a fine sandy loam. Forage radish (Raphanus sativus L.) and winter pea (Pisum sativum subsp. arvense L.) decomposition rate and N release trend were compared with cereal rye (Secale cereale L.), as the conventionally grown cover crop in Massachusetts, to evaluate if forage radish or winter pea would provide more N for early planted crops in the spring than cereal rye. Forage radish produced the highest dry matter yield (3.46 Mg ha−1) followed by winter pea (3.1 Mg ha−1) and cereal rye (2.42 Mg ha−1). All of the cover crops had a faster residue decomposition and release of N when buried in the soil. Through the decomposition period, forage radish and winter pea lost their initial biomass and N concentration faster than cereal rye in both BR and SR due to higher C/N ratio and lignin concentration in rye. Our results showed a greater potential of forage radish or winter pea for a synchronous N release relative to crop N demands early in the spring than with cereal rye.Core Ideas Forage radish has great potential for synchronous N release with cash crop N demands early in the spring. A high N yielding winterkilled cover crop is preferred over rye if early planting of cash crop is target. Rye may not provide the succeeding crop with sufficient N when terminated early.

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Attaining h igh switchgrass (Panicum virgatum L.) yields with optimum quality for combustion while also maintaining crop health is challenging. A 3-yr study was conducted at the Crops and Animal Research and Education Farm of the University of Massachusetts in South Deer eld, MA, from 2009 to 2012 to assess the in uence of harvesting season and N application rates on biomass yield, mineral content of the grass, non-structural carbohydrate (NSC) reserves in the roots, as well as nitrogen use eciency (NUE) of switchgrass (cultivar Cave-in-Rock) grown for combustion. Delaying harvest from summer until spring reduced the biomass yield by 27%. e highest biomass production (7.82 Mg ha -1 ) was obtained from summer harvest in the rst growing season. Averaged over 3 yr, increasing N application rate up to 134 kg ha -1 resulted in the highest biomass production in the summer harvest with 7.41 Mg ha -1 . Nutrient concentrations in the grass were dependent on the season of harvest. In general, delaying the harvest reduced N, P, K, and Mg content in the feedstock. Lower N application rate resulted in higher agronomic e ciency (AE) and NUE. Peak NSC concentrations in belowground tissues were measured in fall and were two times higher than those in summer and spring. ese data suggest that not more than 67 kg N ha -1 combined with fall harvest maintain switchgrass yield and quality for combustion processes.

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Concerns about P enrichment of soil, streams, and lakes, NH 3 emissions from surface-applied manure, and increasing N fertilizer costs have resulted in greater adoption of manure incorporation at rates that approximate P removal. A 5-yr field study was conducted comparing the influence of annual spring applications of N-vs. P-removal-based compost (74 and 46 Mg ha −1 wet basis, respectively), liquid dairy manure (196 and 68 kL ha −1 , respectively), and sidedress N fertilizer (0 and 112 kg ha −1 ) on soil pH, soil organic matter (sOM), respiration, NO 3 -N, and soil test P (sTP) and K (sTK) in a corn (Zea mays L.) silage cropping system on a calcareous central New York soil. Manure was incorporated with tillage in the P-removal-based system. After 5 yr, soil pH (0-20 cm) remained unchanged compared with its initial level in 2001 regardless of the application rate or source. In P-based manure and inorganic N plots, sOM declined with time but increased by 4 g kg −1 with N-based compost. solvita CO 2 respiration increased only for N-based compost (41 g mg −1 ), which was greater than for P-based manure (32 g mg −1 ) in April 2005. After 5 yr, topsoil (0-20 cm) sTP and sTK were greatest with N-based compost and manure. These results show the benefits of compost application for sOM accumulation and respiration, the benefits of P-based applications for management of sTP and sTK, and the negative impact on sOM because of tillage incorporation of manure at P-based rates. Manure injection rather than tillage-based incorporation might counteract this negative impact.Abbreviations: SOC, soil organic carbon; SOM, soil organic matter; STK, soil test potassium, STP, soil test phosphorus. In New York, dairy farming is the largest agricultural industry (National Agricultural Statistics Service, 2009). Manure generated on the dairy farms is typically land applied as liquid or semisolid material. When manure is surface applied at rates to meet the N requirement of a corn crop, the typical result is overfertilization of P and K due to the lower N/P and N/K ratios of manure than plant tissues. Overapplication of P and K increases STP and STK with time (Eghball 1999;Wu and Powell, 2007;Sadeghpour et al., 2016), which may be desirable if initial STP and STK are low but can lead to an increased risk of P runoff (Kleinman et al., 2002) and high-K forages (Cherney et al., 1998) with time.Some farms separate solids for reuse as bedding or to be composted for sale or application to distant fields. Composting is a useful option to reduce the volume of fresh manure and reduce odor issues (Eghball, 2002). Other advantages of composting are reduced numbers of viable weed seeds and pathogenic microorganisms (Diacono and Montemurro, 2010). A major disadvantage of compost is the loss of C and N during the composting process itself, resulting in N/P and N/K ratios that can be greater than the expected ratios for crop needs than untreated manure (Eghball, 2002 Core Ideas• Annual application of manure to corn at P-removal based rates will reduce P...

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.