Can char carbon enhance soil properties and crop yields in low-carbon soils?

Restoring soil carbon (C) lost due to intensive farming is a long-term endeavor under current conservation management practices. Application of coal combustion residue (293 g C kg^-1 ) from a sugar beet (Beta vulgaris L.) processing factory, hereafter referred to as char, could rapidly restore soil C and productivity in degraded croplands, but data on this potential strategy are unavailable. We assessed the impacts of char application to two relatively low-C soils (10.1 and 12.2 g C kg^-1 ) and one relatively high-C soil (17.3 g C kg^-1 ) on soil C, soil physical and fertility properties, and crop yields in no-till systems in the Great Plains after 2 yr. Char was disked to 15 cm soil depth at char-C application rates ranging from 0 to 19.7 Mg C ha^-1 , corresponding to char application rates ranging from 0 to 67.3 Mg ha^-1 . The highest char rate increased C concentration in all soils but increased C stock only in low-C soils. Char did not affect soil penetration resistance, available water, aggregate stability, most nutrients, and crop yields. Char application at high rates increased sulfate, Ca, Mg, and Na concentrations but did not influence other properties. Carbon recovery of the char applied at the highest rate varied among soils from 50 to 85%, but the mechanisms for such differences need further investigation. Short-term duration, low char C concentration, and low application rates may explain the limited char effects. Overall, char application at 19.7 Mg char-C ha^-1 (i.e., 67.3 Mg char ha^-1 ) increased soil C concentration but had negligible effects on other soil properties and crop yields after 2 yr.

Determining the Efficacy of a Hybridizing Agent in Wheat (Triticum aestivum L.)

Hybrid wheat (Triticum spp.) has the potential to boost yields and enhance production under changing climates to feed the growing global population. Production of hybrid wheat seed relies on male sterility, the blocking of pollen production, to prevent self-pollination. One method of preventing self-pollination in the female plants is to apply a chemical hybridizing agent (CHA). However, some combinations of CHA and genotypes have lower levels of sterility, resulting in decreased hybrid purity. Differences in CHA efficacy are a challenge in producing hybrid wheat lines for commercial and experimental use. Our primary research questions were to estimate the levels of sterility for wheat genotypes treated with a CHA and determine the best way to analyze differences. We applied the CHA sintofen (1-(4-chlorphyl)-1,4-dihydro-5-(2-methoxyethoxy)-4-oxocinnoline-3-carboxylic acid; Croisor 100) to 27 genotypes in replicate. After spraying, we counted seed in bagged female heads to evaluate CHA efficacy and CHA-by-genotype interaction. Using logit and probit models with a threshold of 7 seeds, we found differences among genotypes in 2015. Sterility was higher in 2016 and fewer genotypic differences were found. When CHA-induced sterilization is less uniform as in 2015, zero-inflated and hurdle count models were superior to standard mixed models. These models calculate mean seed number and fit data with limit-bounded scales collected by agronomists and plant breeders to compare genotypic differences. These analyses can assist in selecting parents and identifying where additional optimization of CHA application needs to occur. There is little work in the literature examining the relationship between CHAs and genotypes, making this work fundamental to the future of hybrid wheat breeding.