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Guangyao Wang, Mathieu Ngouajio, and Darryl D. Warncke

systems, cultivated muck soils may subside up to 3 cm every year because of wind erosion, compaction, and organic matter oxidation ( Hoffmann et al., 1996 ). A cover crop planted after harvest of the cash crop may help reduce soil erosion and compaction

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Robert L. Meagher Jr., Rodney N. Nagoshi, James T. Brown, Shelby J. Fleischer, John K. Westbrook, and Carlene A. Chase

Sunn hemp, Crotalaria juncea L., is a warm-season legume that is planted before or after a vegetable cash crop to add nutrients and organic matter to the soil ( Cherr et al., 2006 , 2007 ; Mansoer et al., 1997 ; Wang et al., 2005 ). This cover

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Daniel C. Brainard and D. Corey Noyes

Management practices that build soil organic matter (SOM) are valuable for improving soil water-holding capacity, nutrient retention, aeration, and infiltration rates ( Magdoff and van Es, 2000 ) . For carrots ( Daucus carota subsp. sativa), these

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Rebecca L. Darnell, Jeffrey G. Williamson, Deanna C. Bayo, and Philip F. Harmon

adaptation ( Penella et al., 2015 ). Cultivated blueberry ( Vaccinium species) have strict soil requirements for optimum growth. These include low pH (4.0–5.5), high organic matter, good aeration and drainage ( Williamson et al., 2018 ), and readily

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Bruno Casamali, Rebecca L. Darnell, Alisson P. Kovaleski, James W. Olmstead, and Jeffrey G. Williamson

al., 2009 ; Strik and Buller, 2014 ). Soils suitable for blueberry production must be acidic (pH 4.0 to 5.5), well aerated with good drainage, high in organic matter ( Williamson et al., 2012 ), and have readily available iron (Fe) and ammonium

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Ashley A. Thompson and Gregory M. Peck

N plus the inorganic N (NH 4 -N and NO 3 -N) ( Campbell-Nelson, 2015 ). Table 1. The carbon to nitrogen ratio (C:N), organic matter (OM), total C, organic N, nitrogen as ammonium (NH 4 -N), nitrogen as nitrate (NO 3 -N), phosphorus (P), and potassium

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Jin-wei Zhang, Yi-xue Liu, Jin-ping Yu, Wei Zhang, Ya-qiong Xie, and Ning-ning Ge

, hydrolyzable nitrogen, rapidly available phosphorus, rapidly available potassium, and organic matter) and soil physical properties (clay content and soil density) for the 0- to 25-cm soil layer were analyzed by the Tianjin Institute of Resource and

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Carl J. Rosen and Cindy B.S. Tongn

Two on-farm field studies were conducted in 1996 and repeated in 1997 to determine the effects of soil amendments and scape (flower stalk) removal on yield, dry matter partitioning, and storage quality of hardneck garlic (Allium sativum L.). One study site was on a loamy sand soil with low organic matter and fertility and the other site was on a sandy loam soil with high organic matter and fertility. Soil amendment treatments tested at both sites were: 1) no amendment, 2) composted manure, and 3) inorganic fertilizer according to soil test recommendations. A fourth treatment, dried, composted turkey-manure-based fertilizer, was included at the low organic matter site. Scapes were removed at the curled stage from plants in half of the harvest rows. Scapes from the remainder of the harvest row plants were allowed to mature until harvest. In 1997, bulbs from each treatment were stored at 0 to 3 °C or 19 to 21 °C for 6 months. Soil amendment treatments had no effect on total garlic bulb yield, dry mass partitioning, or stored bulb weight loss at the sandy loam, high organic matter site. Manure compost, fertilizer, and composted turkey manure soil amendments reduced the yield of smaller bulbs compared with the control at the loamy sand, low organic matter site. The proportion of bulbs >5 cm was highest with the manure compost treatment. At the low organic matter site, scape removal resulted in a 15% increase in bulb yield and an increase in bulb size compared with leaving scapes on until harvest (P = 0.05). At the high organic matter site, scape removal increased bulb yield by 5% (P = 0.10). Scape removal increased dry matter partitioning to the bulbs, but had no effect on total (scape + shoot + bulb) aboveground dry matter production. The increase in bulb dry mass when scapes were removed was offset by an increase in scape dry mass when scapes were left on. Bulb weight loss in storage was less at 0 to 3 °C than 19 to 21 °C. Soil amendments only affected bulb storage quality at the loamy sand, low soil organic matter site. The effect of scape removal on bulb weight loss was nonsignificant at either location.

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Ajay Nair and Brandon Carpenter

organic matter and ash that remains after organic matter is thermally decomposed in a low-oxygen environment ( Lehmann and Joseph, 2009 ). Biochar addition has been shown to impart beneficial chemical and physical attributes to mineral soils ( Barrow, 2012

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Joan R. Davenport and Carolyn DeMoranville

Soluble nitrogen (ammonium and nitrate) is released when soil organic matter is mineralized. The amount of N released by this process depends on the amount of organic matter present and soil temperature. Cranberry (Vaccinium macrocarpon Ait.) grows in acidic soils with a wide range in organic matter content. To evaluate how soil N release is affected by soil temperature, intact soil cores were collected from sites that had received no fertilizer and placed in PVC columns. Four different soil types, representing the range of cranberry soils (sand, sanded organic soil, peat, and muck), were used. Each column was incubated sequentially at six different temperatures from 10 to 24 °C (2.8 °C temperature intervals) for 3 weeks at each temperature, with the soils leached twice weekly to determine the amount of N release. The total amount of N in leachate was highest in organic soils, intermediate in the sanded organic soil, and lowest in the sands. The degree of decomposition in the organic soils was important in determining which form of N predominated. In the more highly decomposed organic soil (muck), most of the N was converted to nitrate. The data from this study resulted in the development of two models—one predicting the N mineralization and the other predicting the proportion of N in each of the two forms. Key factors for N release rate were soil temperature, percentage of clay, and organic carbon content. For predicting the proportion of N as ammonium vs. nitrate, key factors were soil temperature, soil pH, and the distribution of mineral matter in the silt and sand fractions.