Rice-residue biochar influences phosphorus availability in soil with contrasting P status

ABSTRACT

Thermo-chemical conversion of crop residues to produce biochar is an emerging strategy in the context of sustainable phosphorous (P) use and residue management. An incubation study for 90 d was conducted to investigate the effects of rice-residue biochar (0, 10, 20 and 40 g kg^?1) in combination with inorganic-P (KH₂PO₄) (0, 25 and 50 mg kg^?1) on phosphorous availability in medium- and high-P status soils. Increasing biochar addition rates alone or in combination with inorganic-P resulted in a significant increase in P pools, i.e. plant available P or Olsen-P (from 8 to 132 mg kg^?1 in medium-P and 15 to 160 mg kg^?1 in high-P soils), microbial biomass P and various mineral-bound inorganic-P fractions in the order (Ca-P > organic-P > Al-P > loosely held/soluble-P > Fe-P > reductant soluble-P). Further, lower phosphatase activity (19–50%) with increasing rates of biochar addition in both soils elucidates the ability of biochar to act as a long-term source of available P in the experimental soils. The results demonstrate that rice-residue biochar can directly or indirectly enhance the status of available P in soils and hence can be used as a beneficial amendment to meet the crop P demand.     

Application of Soil and Plant Analysis for Applied Research and Development in West Asia–North Africa: An International Center's Perspective

Abstract

The networks of 15 international research centers around the globe that are sponsored by the Consultative Group for International Agricultural Research (CGIAR) seeks to alleviate poverty in the developing world through enhanced production, while maintaining biodiversity and the sustainability of natural resources. The mandate of the International Center for Agricultural Research in the Dry Areas (ICARDA) is to focus on improving semi‐arid cropping systems in the drought‐prone West Asia and North Africa region. Since its inception in 1997, ICARDA's soil laboratory played a pivotal role in backstopping the institution's on‐station and on‐farm research in Syria and its collaborative research with the region's national programs. This article gives an overview of the evolution of soil and plant analysis in serving the center's mission. A major effort was the regional soil test calibration program, which set the basis for rational use of fertilizers and the identification of related nutrient constraints. Such analyses were extensively employed in all the long‐term dryland cropping system trials and later in irrigated agriculture and the interface between plant nutrition and crop breeding. Major emphasis was given to improving and upgrading analytical services in the region's laboratories. Despite advances made in analytical methodology, the challenge is to apply to solving real problems in the service of humanity.     

Evaluation of Agronomic and Environmental Soil P Test Methods in a Network of Hungarian Long‐Term Field Trials

Abstract

Winter wheat shoot weight and phosphorus (P) concentrations, corn leaf weight and P concentrations, and soil AL, Olsen, H₂O, Bray 1, Pi (Fe-oxide impregnated paper strip) and AERM (anion exchange resin membrane) contents were determined in a network of uniform Hungarian national long‐term field trials. P application had a significant effect on soil P test values at different P levels and sites. The relationship between the different soil P test methods was studied separately for different soil groups (all, acid, and calcareous soils). Corn leaf weight was influenced by the sites much more than by soil P supply level, whereas corn leaf P percentage was influenced by both sites and P levels. For winter wheat, both sites and soil P levels had a positive effect on wheat shoot weight. Wheat shoot P percentage was influenced by the soil P supply much more than by the sites. Correlation between corn leaf P percentage and the Pi or AERM extractable P and between wheat shoot P percentage and the Pi and AERM P values was logarithmic.     

Heavy‐Metal Concentration of Sewage‐Contaminated Water and Its Impact on Underground Water,Soil, and Crop Plants in Alluvial Soils of Northwestern India

Abstract

Heavy‐metal concentration in underground and surface water, soil, and crop plants growing in farmers' fields near the industrial city of Ludhiana, Punjab, India, that receive irrigation with water contaminated with sewer and untreated industrial effluents was studied. The concentrations of lead (Pb), chromium (Cr), cadmium (Cd), and nickel (Ni) in sewage‐contaminated water were 18, 80, 88, and 210 times higher than in shallow handpump water, and 21, 133, 700, and 2200 times higher than in deep tube‐well water, respectively. The concentrations of Cd and Ni in shallow handpump underground water were significantly higher than in deep tube‐well underground water. The concentrations of Pb, Cr, Cd, and Ni in deep tube‐well water were 0.017, 0.003, 0.0002, and 0.0002 mg L^?1, respectively. Soils irrigated with sewage‐contaminated water had higher electrical conductivity, cation exchange capacity, organic carbon (C), and clay content but had lower pH and calcium carbonate content compared to soils irrigated with deep underground water. The concentrations of diethylenetriamine pentaacetic acid (DTPA)–extractable Pb, Cr, Cd, and Ni in soils irrigated with sewage‐contaminated water were 1.8, 35.5, 3.6, and 14.3 times higher, and total concentrations of these heavy metals were 1.5, 3.0, 3.7, and 2.2 times higher than that in soils irrigated with deep underground water. The mean concentrations of Pb, Cr, Cd, and Ni in crop plants growing on soils irrigated with sewage‐contaminated water were 4.88, 4.20, 0.29, and 3.99 mg kg^?1, which were 1.2, 2.1, 8.7, and 1.9 times higher than in plants irrigated with deep tube‐well water, respectively. The amounts of potentially toxic metals were significantly and positively correlated with cation exchange capacity and organic C content and negatively correlated with soil pH. In conclusion, long‐term accumulation of toxic metals in soils and their uptake by crop plants has a high potential for phytotoxicity as well as for entering into the food chain. The findings also suggest contamination of underground shallow drinking water through leaching of some highly mobile metals.     

Coal Fly Ash and Phospho‐gypsum Mixture as an Amendment to Improve Rice Paddy Soil Fertility

Abstract

Rice is a plant that requires high levels of silica (Si). As a silicate (SiO₂) source to rice, coal fly ash (hereafter, fly ash), which has an alkaline pH and high available silicate and boron (B) contents, was mixed with phosphor‐gypsum (hereafter, gypsum, 50%, wt wt^?1), a by‐product from the production of phosphate fertilizer, to improve the fly ash limitation. Field experiments were carried out to evaluate the effect of the mixture on soil properties and rice (Oryza sativa) productivity in silt loam (SiL) and loamy sand (LS) soils to which 0 (FG 0), 20 (FG 20), 40 (FG 40), and 60 (FG 60) Mg ha^?1 were added. The mixture increased the amount of available silicate and exchangeable calcium (Ca) contents in the soils and the uptake of silicate by rice plant. The mixture did not result in accumulation of heavy metals in soil and an excessive uptake of heavy metals by the rice grain. The available boron content in soil increased with the mixture application levels up to 1.42 mg kg^?1 following the application of 60 Mg ha^?1 but did not show toxicity. The mixture increased significantly rice yield and showed the highest yields following the addition of 30–40 Mg ha^?1 in two soils. It is concluded that the fly ash and gypsum mixture could be a good source of inorganic soil amendments to restore the soil nutrient balance in rice paddy soil.     

Soil and Plant Analysis Council: A Model for Scientific Innovation,Education, and Development

Soil and plant analysis has been a major contribution to the development of the agricultural sciences and indirectly to sustaining mankind. The advances that have occurred in the various disciplines in soil science, agronomy, and crop science would have been impossible without parallel advances in analytical technology. Despite the many divisions in the journals of the Soil Science Society of America, Crop Science Society of America, and American Society of Agronomy, none is solely devoted to the discipline of analysis of soils and plants and related areas. However, the Soil and Plant Analysis Council (SPAC) fills that critical void because it is an international society of scientists, educators, and private and public organizations with a common interest in promoting analysis of soils, plants, water, manure, and fertilizers. The primary emphasis is on nutrients in relation to crop production and increasing environmental issues. The main goal of SPAC is to provide leadership in the development and dissemination of methodology, interpretation, and application of analysis for efficient resource management and environmental protection. Its activities include publications (methods handbooks, symposia and workshop proceedings, newsletter), liaising with national agencies and commercial organizations to standardize and improve analytical procedures, maintenance of a laboratory directory, and holding international symposia. The Council has played a significant role in expanding the breadth, depth, and scope of analytical technologies in North America as well as internationally.