Deterministic and stochastic yield response plateau functions were estimated to determine the expected profit-maximizing nitrogen rates, yields, and net returns for corn grown after corn, cotton, and soybeans. The stochastic response functions were more appropriate than their deterministic counterparts, and the linear response stochastic plateau described the data the best. The profit-maximizing nitrogen rates were similar for corn after corn, cotton, and soybeans, but relative to corn after corn, the expected corn yield plateaus increased by 12% and 16% after cotton and soybeans, respectively. Expected net returns increased for corn after cotton and soybeans relative to corn after corn.

Planting date is one of the main factors affecting soybean (Glycine max [L.] Merr.) yield. Environmental conditions in the US Midsouth allow for planting dates from late March through early July, and maturity groups (MGs) ranging from 3 to 6. However, the complexity of interactions among planting date, MG, and the environment makes the selection of an optimum MG cultivar difficult. A regional 3‐yr study, conducted at eight locations with latitudes ranging from 30.6 to 38.9°N, planting dates ranging from late March to early July, and MGs 3 to 6, was used to examine the relationship between relative yield and planting day. The data indicated that yield was dependent on the location and MG choice. There was a quadratic response of relative yield to planting day in six out of the eight locations studied for MG 3 cultivars, and in five locations for MG 4 cultivars. On the other hand, MG 5 and 6 cultivars were more likely to have a negative linear relationship, with a quadratic response in only two of the eight locations. Optimum planting dates that maximized yield were dependent on the location and MG combination and ranged from 22 March to 17 May. Delaying planting dates from mid May to early June reduced yields by 0.09 to 1.69% per day, with the rate of decline greatest at the southern‐most locations. Overall, MG 4 cultivars maximized yield or were not statistically different from the highest yielding MG at most locations and planting dates.

New urease and nitrification inhibitors and polymer coatings were introduced in recent years, but their effects on N loss and plant N nutrition were scarcely examined in agronomic no-tillage production systems. A field experiment of urea treated with efficiency enhancers was conducted on no-tillage corn ( Zea mays L.) in Tennessee, the USA during 2013–2015. A field experiment on urea and ammonium nitrate (UAN) treated with efficiency enhancers was carried out on no-tillage corn in Tennessee in 2014 and 2015. Urea treated with N-(n-butyl) thiophosphoric triamide (NBPT) at concentrations of 20% (NBPT 1 ), 26.7% (NBPT 2 ), or 30% (NBPT 3 ) and polymer coated urea (PCU) were effective but maleic-itaconic copolymer treated urea was ineffective in reducing ammonia volatilization loss and improving N nutrition, grain yield, and N agronomic use efficiency of corn compared with untreated urea. Specifically, NBPT 1 , NBPT 2 , or NBPT 3 treated urea and PCU reduced the total ammonia volatilization loss by 29.1–78.8%, 35.4–81.9%, 77.3–87.4%, and 59.1–83.3% during the 20 days after N applications, but increased grain yield by 15.6–31.4%, 12.9–34.8%, 18.7–19.9%, and 14.6–41.1%, respectively. The inhibitory effect of NBPT on ammonia volatilization did not improve with NBPT concentration increased from 20% to 30%. UAN treated with NBPT 3 or a combination of urease and nitrification inhibitors resulted in 16.5–16.6% higher corn yield than untreated UAN only when they were surface applied. In conclusion, when urea-containing fertilizers are surface applied without any incorporation into the soil under no-tillage, their use efficiencies and performances on corn can be enhanced with an effective urease inhibitor in areas and years with noticeable urea N losses.

Sorghum is an important cereal with reported health benefits. The objectives of this study were to measure the biological activities of alcoholic extracts of ten sorghum varieties and to determine the association between the color of the extracts and their biological activities. Variation on concentrations of bioactives among sorghum varieties was observed with ethanolic extracts giving higher concentrations than methanolic extracts. The color of the extracts significantly correlated with the concentrations of bioactives and with nitric oxide scavenging activity. Freeze-dried ethanol extract is more potent than freeze-dried methanol extract and caused cytotoxicity to A27801AP and PTX-10 OVCA with ED50 values of 0.69 and 1.29 mg mL(-1), respectively. Pre-treatment of OVCA with ethanol extract led to chemosensitization to paclitaxel and the proliferation and colony formation of OVCA cells were reduced by 14.7 to 44.6% and 36.4 to 40.1%, respectively. Sorghum is a potential source of colorants with health promoting properties. This is the first report on the capability of sorghum alcoholic extracts to cause cytotoxicity and chemosensitize ovarian cancer cells in vitro.