Agriculture

  2009 NOV 26 - (VerticalNews.com) -- According to a study from Grugliasco, Italy, "Fragipan is a widely distributed subsoil horizon that induces severe limitations to plant growth and land use, mainly because of its high bulk density. In this work, we evaluated the pore-size distribution through the analysis of the cumulative curve of intruded mercury volume in some soils with fragipan horizons."

  "This approach provides information also about the arrangement of particles, thus we compared the results obtained for fragipan and nonfragipan horizons to relate porosity and particle arrangement with the specific physical properties of fragipans. The total volume of intruded mercury did not allow to discriminate between fragipan and nonfragipan horizons. However, from the variation of the pore volume as a function of the radius, two modal classes of pores were found, coarse and fine, respectively. The fine-pore class arose from the arrangement of clay particles, and its volume was correlated to clay contents (r = 0.787) and to clay packing density (r = -0.621). The clay fractions in fragipans were less densely packed than in the other B horizons, even if they had similar clay contents. The coarser-pore modal class is known to arise from the interactions between clay, silt, and sand particles, and its volume was different among horizons. Fragipan had a low volume of this modal pore class. In addition, a packing density for the coarser phase of 0.74, corresponding to a rhombohedral packing, was found only in fragipans. Thus, the low permeability and high bulk density of fragipans are linked to specific arrangements of the particles: an open packing of the clay phase is associated to an extremely dense packing of silt and sand," wrote G. Falsone and colleagues, University of Turin ...read more

  2009 NOV 26 - (VerticalNews.com) -- "Potato (Solanum tuberosum L.), an important food crop, generally requires a high amount of phosphate fertilizer for optimum growth and yield. One option to reduce the need of fertilizer is the use of P-efficient genotypes," scientists in Hannover, Germany report.

  "Two efficient and two inefficient genotypes were investigated for P-efficiency mechanisms. The contribution of root traits to P uptake was quantified using a mechanistic simulation model. For all genotypes, high P supply increased the relative growth rate of shoot, shoot P concentration, and P-uptake rate of roots but decreased root-to-shoot ratio, root-hair length, and P-utilization efficiency. Genotypes CGN 17903 and CIP 384321.3 were clearly superior to genotypes CGN 22367 and CGN 18233 in terms of shoot-dry matter yield and relative shoot-growth rate at low P supply, and therefore can be considered as P-efficient. Phosphorus efficiency of genotype CGN 17903 was related to higher P-utilization efficiency and that of CIP 384321.3 to both higher P-uptake efficiency in terms of root-to-shoot ratio and intermediate P-utilization efficiency. Phosphorus-efficient genotypes exhibited longer root hairs compared to inefficient genotypes at both P levels. However, this did not significantly affect the uptake rate and the extension of the depletion zone around roots. The P inefficiency of CGN 18233 was related to low P-utilization efficiency and that of CGN 22367 to a combination of low P uptake and intermediate P-utilization efficiency," wrote T. Balemi and colleagues ...read more

  2009 NOV 26 - (VerticalNews.com) -- According to recent research published in the Journal of Plant Nutrition and Soil Science - Zeitschrift Fur Pflanzenernahrung und Bodenkunde, "Incubation and pot experiments were conducted to investigate the impact of commercially distributed biofertilizers (effective microorganisms [EM], BIOSTIMULATOR, BACTOFIL-A, and BACTOFIL-B) on soil microbial-biomass content and activity, net N mineralization in soil, and growth of Lolium perenne. According to the manufacturers, the products tested are based on microbial inoculants or organic growth stimulants, and are supposed to influence soil microbial properties and improve soil conditions, organic-matter decomposition, and plant growth. ...read more