Early high‐moisture wheat harvest improves double‐crop system: I. Wheat yield and quality

Abstract

Double cropping winter wheat (Triticum aestivum L.) and soybean [Glycine max (L.) Merr.] increases total food production without additional land. However, yield and/or quality of both crops often suffer if wheat harvest is delayed beyond maturity. We evaluated the impact of high‐moisture wheat harvest on wheat yield and quality and soybean planting time across eighteen site‐years in five Mid‐Atlantic states during 2015 to 2017. Wheat was harvested three to five times beginning at 150 to 200 g kg−1 moisture at 4 to 14 d intervals. High‐moisture wheat harvest facilitated 4 to 21 d earlier soybean planting. Grain moisture generally decreased with harvest date, but temperature and rainfall varied moisture content. Wheat test weight declined linearly 2.91 to 4.87 kg m−3 d−1 delay in harvest. Wheat relative yield was not affected by delayed harvest in Pennsylvania but declined linearly 2.6% per day delay in harvest after 4 July in Maryland, 0.55% after 30 June in Delaware, 3.1% after 19 June in Virginia, and 0.42% after 4 June in North Carolina. Test weight was positively associated with relative yield and explained 37 to 82% of relative yield variability. Critical days for desirable test weight were similar to the critical harvesting days for maximum yield, indicating that test weight is an excellent predictor of optimum harvesting day. Delayed harvest decreased grain falling number but increased softness equivalent. Overall, high‐moisture wheat harvest improved wheat yield and quality by reducing test weight loss and would allow earlier soybean planting to maximize growth and yield.

Early high‐moisture wheat harvest improves double‐crop system: II. Soybean growth and yield

“…Parvej et al. (2020) illustrated that early high‐moisture wheat harvest beginning at 18–20% moisture until normal harvest at 13–15% moisture facilitates double‐crop soybean planting 4–21 d earlier, depending on the site‐year. Double‐crop soybean yield loss due to delayed planting from mid‐June to late July in this study was within the range of 10–70% yield loss reported by several researchers under different agroclimatic conditions, water management, and soil types (Barreiro & Godsey, 2014; Bastidas et al., 2008; Beatty, Eldridge, & Simpson, 1982; Board & Hall, 1984; Boquet, Koonce, & Walker, 1982; Carter & Boerma, 1979; Chen & Wiatrak, 2010; De Bruin & Pedersen, 2008; Egli & Bruening, 2000; Egli & Cornelius, 2009; Heatherly, 1988; Kane, Steele, & Grabau, 1997; Oplinger & Philbrook, 1992; Parker et al., 1981; Parvez, Gardner, & Boote, 1989; Popp et al., 2002).…”

“…All sites were classified as somewhat well drained to well drained, with soil textures ranging from loamy sand to silt loam, organic matter from 8 to 30 g kg −1 , estimated cation exchange capacity from 2.4 to 9.3 cmol c kg −1 , and pH from 5.4 to 7.0. At each site, double‐crop soybean was planted immediately after high‐moisture wheat harvest (15–20% moisture; Parvej et al., 2020) three to five times at a 4‐ to 14‐d interval, depending on the state (Table 2). Planting dates ranged from 1 June to 30 July.…”

“…The experiment was designed as a randomized complete block in a split‐plot arrangement with four to six blocks, where the main plot was planting date and the subplot was soybean cultivar. The planting dates within each block were laid out following wheat harvest dates that were randomly assigned prior to the first harvest (Parvej et al., 2020), and soybean cultivars were randomly laid out within each planting dates. Each subplot of soybean cultivar was 7.3 m long by 1.9 m wide.…”

Generalized Mathematical Model of the Grain Drying Process

“…S i(ou) = S i(in) + ∆S g(lo) + ∆S g(dr) + ∆S g(un) S w(ou) = S w(ou) − ∆S w S a(in) = S a(in) S g(in) + S i(in) + S w(in) + S g + S i + S w ≤ E (lo) S g(ou) + S i(ou) + S w(ou) + S g + S i + S w ≤ E (un) (3) where: ∆S g(dr) is loss of grain dry matter during drying; ∆S w is water stream evacuated from dried grain; S g , S i , and S w are mixing of grain dry matter, impurities, and water streams in a continuous-flow dryer, respectively.…”

“…The drying process is expensive; therefore, food producers have a preference for grain with low moisture content. However, excessive shedding of dehydrated grain during harvest can lead to grain losses [1][2][3]. The optimal moisture content of harvested wheat, barley, rye, and rice grain is 14-17%, but these crops can be harvested already when grain moisture content is 20-22% [4][5][6][7].…”