The use of arsenic (As) contaminated groundwater for irrigation of crops has resulted in elevated concentrations of arsenic in agricultural soils in Bangladesh, West Bengal (India), and elsewhere. Paddy rice (Oryza sativa L.) is the main agricultural crop grown in the arsenic-affected areas of Bangladesh. There is, therefore, concern regarding accumulation of arsenic in rice grown those soils. A greenhouse study was conducted to examine the effects of arsenic-contaminated irrigation water on the growth of rice and uptake and speciation of arsenic. Treatments of the greenhouse experiment consisted of two phosphate doses and seven different arsenate concentrations ranging from 0 to 8 mg of As L(-1) applied regularly throughout the 170-day post-transplantation growing period until plants were ready for harvesting. Increasing the concentration of arsenate in irrigation water significantly decreased plant height, grain yield, the number of filled grains, grain weight, and root biomass, while the arsenic concentrations in root, straw, and rice husk increased significantly. Concentrations of arsenic in rice grain did not exceed the food hygiene concentration limit (1.0 mg of As kg(-1) dry weight). The concentrations of arsenic in rice straw (up to 91.8 mg kg(-1) for the highest As treatment) were of the same order of magnitude as root arsenic concentrations (up to 107.5 mg kg(-1)), suggesting that arsenic can be readily translocated to the shoot. While not covered by food hygiene regulations, rice straw is used as cattle feed in many countries including Bangladesh. The high arsenic concentrations may have the potential for adverse health effects on the cattle and an increase of arsenic exposure in humans via the plant-animal-human pathway. Arsenic concentrations in rice plant parts except husk were not affected by application of phosphate. As the concentration of arsenic in the rice grain was low, arsenic speciation was performed only on rice straw to predict the risk associated with feeding contaminated straw to the cattle. Speciation of arsenic in tissues (using HPLC-ICP-MS) revealed that the predominant species present in straw was arsenate followed by arsenite and dimethylarsinic acid (DMAA). As DMAA is only present at low concentrations, it is unlikely this will greatly alter the toxicity of arsenic present in rice.

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This study calculates the economic feasibility of converting biomass from black spruce forests into biochar and using it as soil amendment to grow potatoes (Solanum tuberosum L.) and beets (Beta vulgaris L.) to improve food availability in one of Canada's most consistently food insecure provinces. The trees were clear cut for the construction of the controversial Muskrat Falls hydroelectric dam and have been left to decay due to a lack of economically feasible processing options. A stochastic analysis conducted on a biochar production budget of a slow pyrolysis mobile biochar unit reveals fixed and variable cost estimates of $505.14 Mg−1 and $499.13 Mg−1, respectively. Applying the biochar as a soil amendment for local beet or potato production makes the biochar venture profitable. Beet field trial data from the study region using 10 t C biochar application rates increases beet yield from 2.9 Mg/ha to 11.4 Mg/ha with a midline increase of 5.59 Mg/ha. A stochastic analysis with variable prices and yields shows a 0.99 probability of biochar production being profitable when applied to beets at the midline production rate, with an average annualized net return over variable costs of $4,953 ha−1, and maximum annualized net return of $11,288 ha−1, over variable costs. Potato production yields average annualized net returns of $965.48 ha−1 over variable costs, but with much more downside risk, considering the minimum annualized net return of −$318.82 ha−1 over variable costs. Biochar application covers average total costs for beets but not potatoes. Using biochar from forest biomass as a soil amendment presents an opportunity to create a local market for biochar in a remote area of Canada, where biochar may be used as an experimental soil amendment to improve food security.

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A field experiment was conducted on an Aerie Haplaquept soil to study the effect of phosphorus (P) deficiency in soil on the P nutrition and yield of five modern varieties of rice, viz., Purbachi, BR1, BR3, BR14, and BR29, popular with the rice farmers of Bangladesh. Soil-available P in the different plots of the experimental field varied widely, from 2.8 to 16.4 ppm. This plot to plot variation in soil-available P content resulted from differences in the total amounts (0 to 480 kg ha -1 ) of P the plots had received over a period of 8 years in a long-term P fertilizer trial conducted previously in the same field. Phosphorus deficiency in soil drastically reduced the grain yield of all the rice varieties. In severely P deficient plots, where soil-available P was around 3 ppm, the yield was less than 1 ton ha -1 while in plots containing an adequate P level, i.e., >6 ppm, the yield was more than 41 ha -1 . Rice yield increased 1

Core Ideas Biochar applied to sandy, acidic soil increased topsoil pH by 0.5 units. Biochar, fertilizer, or fishmeal alone was unable to support crop establishment, growth, and biomass yield. Biochar along with fertilizer or fishmeal boosted crop establishment, growth, and yields. Topsoil Ca, K, and Mn availability increased by 186, 19, and 2.6 mg L−1 due to biochar application. Plant tissue N, Mg, Fe, Mn, and Zn contents were higher in NBT than in BT, but the opposite was found for K. A multi‐year experiment was conducted in the sandy, acidic soils of Happy Valley–Goose Bay (HV‐GB), Newfoundland and Labrador, Canada to evaluate the effects of hardwood biochar on soil fertility, and to ascertain its nutrient supplying capability when applied singly or in combination with fishmeal and chemical fertilizers. The experiment was set up on a permanent layout and in a randomized block design with 10 treatments resulting from combinations of biochar (20 Mg C ha−1) with half and full recommended doses of fertilizers and fishmeal. In the control and biochar only treatments the beet (Beta vulgaris L.) seedlings did not grow at all, and in the fertilizer or fishmeal alone treatments the survival, growth, and biomass yields were severely affected. However, biochar application along with fertilizer or fishmeal enhanced crop establishment, growth, and yields. Biochar application increased topsoil pH by 0.5 unit and availability of Ca, K, and Mn by 186, 19, and 2.6 mg L−1, respectively. Plant tissue contents of N, Mg, Fe, Mn, and Zn were greater in non‐biochar treatments (NBT) than in biochar treatments (BT), but the opposite was found for K. Despite greater nutrient contents in NBT for some elements, plant uptake (kg ha−1) of nutrients in BT were always much greater than NBT due to higher biomass yield in BT. The positive effects of biochar observed in this study demonstrate that biochar has the potential to enhance soil fertility and crop productivity of sandy, acidic soils that are similar to the regional soils of Labrador.

A ®eld experiment was conducted to study the effect of phosphorus (P) de®ciency on the mineral nutrition of ®ve modern, high-yielding rice varieties, Purbachi, BR1, BR3, BR14, and BRRIDHAN29. The available P in the soils of different plots of the experimental ®eld varied from 2.8 to 16.4 mg kg À 1 . Such a wide range of available P in the different plots resulted from differences in the amounts of P (0 to 480 kg ha À 1 ) applied over a period of 8 years during a previous long-term P fertilizer trial in the same ®eld.The relationship among the P, potassium (K), and magnesium (Mg) concentrations in rice straw and grain in a soil P de®ciency situation were especially noteworthy. The K concentration in rice straw was negatively correlated with the P concentration (r À0.42 to À 0.60), but in the case of grain the coef®cient of JOURNAL