No abstract

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.

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.

Planting cover crops after corn-silage harvest could have a critical role in the recovery of residual N and N from fall-applied manure, which would otherwise be lost to the environment. Experiments were conducted at the University of Massachusetts Research Farm during the 2004-2006 growing seasons. Treatments consisted of oat and winter rye cover crops, and no cover crop, and four cover-crop dates of planting. The earliest planting dates of oat and winter rye produced the maximum biomass yield and resulted in the highest nitrate accumulation in both cover-crop species. The average nitrate accumulation for the 3 years in winter rye and oat at the earliest time of planting was 60 and 48 kg ha -1 , respectively. In 2004 where the residual N level was high, winter rye accumulated 119 kg nitrate ha -1 . While initially soil N levels were relatively high in early September they were almost zero at all sampling depths in all plots with and without cover crops later in the fall before the ground was frozen. However, in plots with cover crops, nitrate was accumulated in the cover-crop tissue, whereas in plots with no cover crop the nitrate was lost to the environment mainly through leaching. The seeding date of cover crops influenced the contribution of N available to the subsequent crop. Corn plants with no added fertilizer, yielded 41% and 34% more silage when planted after oat and rye, respectively, compared with the no-cover crop treatment. Corn-silage yield decreased linearly when planting of cover crops was delayed from early September to early or mid-October. Corn-ear yield was influenced more than silage by the species of cover crop and planting date. Similar to corn silage, ear yield was higher when corn was planted after oat. This could be attributed in part to the winter-kill of oat, giving it more time to decompose in the soil and subsequent greater release of N, while the rapidly increasing C : N ratio of rye can lessen availability to corn plants. Early plantings of cover crops increased corn-ear yield up to 59% compared with corn-ear yield planted after no cover crop.

The effects of growing and storage locations and storage temperature on soft scald incidence of `Honeycrisp' apples were examined. In 1999 and 2000, fruits were produced at five different locations, harvested at two different times, and stored at two or five different storage locations. In 1999, fruits were stored at 0 or 2 °C. Soft scald was only observed in fruits from one growing location and primarily at 0 °C. More soft scald was observed from the second harvest than from the first. Scalded fruits were preclimacteric as determined by ethylene production rate, whereas fruits from the other locations were postclimacteric. In 2000, fruits from four of the growing locations developed soft scald, and soft scald incidence was not related to ethylene production rate. Scalded fruits had higher concentrations of phosphorus, boron, and magnesium, and lower concentrations of manganese than unaffected fruit. Development of soft scald was not related to fruit ethylene production rates, was dependent on growing location, increased with later harvest, and may be related to fruit elemental content.