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Pyrolysis of biomass, reduces its volume, mass, odour, and potential pathogens, while concentrating nutrients in the resulting biochar. However, the plant availability of nutrients in particular of nitrogen remains largely unknown. Therefore, we investigated the nutrient availability of carbonized poultry litter. A nutrient poor soil was either fertilized with poultry litter or poultry litter carbonized at 500°C at the rates of 1.5, 3 and 6 t/ha. These organic amendments were compared with corresponding rates of mineral fertilizers (NH4NO3, KCl, CaHPO4, MgSO4) in a pot experiment. After four successive harvests of ryegrass (Lolium sp.) in a greenhouse we analyzed plant nutrient uptake and nutrient concentrations in the soil. While all treatments showed a linear increase in plant growth and nitrogen uptake, the plants fertilized with carbonized poultry litter did not show such a response. The carbonized poultry litter treatment produced more biomass than the unfertilized control, but the tissue concentration of nitrogen was below that of the control. Mehlich 1 extractable nutrients in the soil showed that there is more available phosphorus, potassium, calcium and magnesium in the soil fertilized with the carbonized poultry manure, but these available nutrients were not utilized due to the nitrogen limitation to plant growth. The results clearly show that nitrogen contained in carbonized poultry litter is not available for plants

Legume cover crops can supply a significant amount of nitrogen (N) for cash crops, which is particularly important for organic farmers. Because N mineralization from cover crop residue depends on the amount of biomass, cover crop quality, as well as environmental conditions such as soil moisture and temperature, predicting the amount of N mineralized and the timing of release has been difficult. We have developed a Cover Crop Nitrogen Calculator based on the N subroutine of the CERES crop model and evaluated the use of the predicted N credits on yields of fall broccoli [Brassica oleracea L. (Italica group)] at a research farm and two working farms. Research farm trials consisted of a cowpea (Vigna unguiculata L. Walp.) cover crop and no cover crop treatments, each at four N rates (0N, 0.5N, 1N and 1.5N, with 1N the target N rate of 112 kg N ha−1 in 2013 and 168 kg N ha−1 in 2014 and 2015) in a randomized complete block design. On-farm trials consisted of a cowpea or sunn hemp (Crotolaria juncea L.) cover crop at four N rates (0N, 0.5N, 1N and 1.5N) and no cover crop treatment at the 1N rate in a completely randomized design. Cover crop biomass and quality (N%, carbohydrates%, cellulose% and lignin%) were measured and used with a 5-yr average soil moisture and soil temperature from a local weather station to predict an N credit. In the cover crop treatments, the N rate was modified by the predicted credit, while the no cover crop treatment received the full N fertilizer rate either as feathermeal (certified organic fields) or as urea (conventional field). At the research farm, broccoli yield increased up to the 0.5N rate, and there was no difference in yield between the no cover 0.5N rate and the cover crop 0.5N rate in 2013, 2014 and 2105. On-farm, we saw an N response in two site-years. In these site-years, there was no difference between the no cover 1N rate and the cover crop 1N rate. At the third site-year, no N response was seen. Overall, our results showed using the cover crop credit predicted by the Calculator did not reduce yields. The use of a decision support tool such as the Calculator may help farmers better manage N fertilizer when cover crops are used, and increase cover crop adoption. [ABSTRACT FROM AUTHOR]

The drought in the southeastern United States over the past two years has made national news. In some areas of Alabama, Georgia, and Florida, surface and ground water sources are [...]

The article presents a study which examines the impact of biochar on nitrogen (N) dynamics in a Norfolk loamy sand with or without ammonium nitrate (NH4NO3). Low-temperature (LT) and high-temperature (HT) biochars from a fast pyrolysis hardwood biochar, switchgrass, poultry litter, pecan shell and peanut hull were investigated. Changes in recalcitrant, resistant, mineralizable and inorganic N fractions were identified after a 127-day (d) incubations which included four leaching events.

Interest in the use of biochar as a soil amendment to increase soil fertility and sequester carbon is increasing. However, the effects of biochar on the survival and reproduction of earthworms are unknown. The toxicity of two different biochars (pine chip and poultry litter char) on Eisenia fetida applied to an artificial soil (70% sand, 20% kaolin, and 10% sphagnum) was investigated at five different application rates of 0, 22.5, 45, 67.5, and 90 Mg ha-1. Earthworm mortality and weight loss reached 100% at the two highest application rates of poultry litter biochar, whereas mortality and weight loss with pine chip biochar did not differ from control treatments. Soil pH, which also increased in controls and pine chip biochar treatments over the course of the incubation, was the most likely cause of earthworm mortality in all treatments. However, it was apparent that poultry litter biochar provided a more stressful environment to earthworms since many worms died in the first five days of incubation. This stressful environment was most likely due to the presence of ammonia gas in addition to high pH, which increased from 7.2 to 8.9 with increasing application rates of poultry litter biochar (pH 10.3). Potentially toxic micronutrients, including As, Zn, Cu, Fe, and Al, present at sub-toxic levels in poultry litter biochar treatments on an individual basis were not likely to have contributed to earthworm mortality; additive effects, however, were not established. Poultry litter biochar also had high Na and Mg content, which could have led to high salinity. As biochar characteristics depend on the feedstock and conditions of pyrolysis, toxicity screening of biochars, particularly those likely to increase soil pH, prior to land application is recommended. [ABSTRACT FROM AUTHOR]

Biochar additions to degraded soils have the potential to improve crop yield and soil quality. We hypothesize that the biochar production process can be tailored to form designer biochars that have specific chemical characteristics matched to selective chemical and/or physical issues of a degraded soil. We produced biochars from peanut hulls, pecan shells, poultry litter, and switchgrass at temperatures ranging from 250°C to 700°C. Biochars were characterized by % mass recovery and by their physical and chemical distinctiveness. These were mixed at 2% w/w with a Norfolk loamy sand (fine-loamy, kaolinitic, thermic Typic Kandiudults) and were laboratory incubated to examine changes in the Norfolk's soil properties. Higher pyrolysis temperatures resulted in lower biochar mass recovery, greater surface areas, elevated pHs, higher ash contents, and minimal total surface charge. Removal of volatile compounds at the higher pyrolysis temperatures also caused biochars to have higher percentages of carbon (C) but much lower hydrogen (H) and oxygen (O) contents. 13C NMR spectral analyses confirmed that aliphatic structure losses occurred at the higher pyrolysis temperatures, causing the remaining structures to be composed mostly of poly-condensed aromatic moieties. Biochars produced at higher pyrolysis temperatures increased soil pH values, while biochar made from poultry litter feedstock grossly increased Mehlich-1 extractable phosphorus (P) and sodium (Na) concentrations. Water-holding capacity varied after biochar incorporation. Biochars produced from different feedstocks and under different pyrolysis conditions influenced soil physical and chemical properties in different ways; consequently, biochars may be designed to selectively improve soil chemical and physical properties by altering feedstocks and pyrolysis conditions. [ABSTRACT FROM AUTHOR]