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The use of organic amendments improves the quality and increases the fertility of the soils due to their adsorption properties, stimulates nutrient cycling and can be used to reduce the availability of heavy metals. The main objective of the research was to evaluate the effect of biochar (BC) derived from pig manure on the availability of Pb in a contaminated and limed agricultural soil. A randomized experimental design was applied, the pig manure was dried at room temperature (23 °C) and pyrolyzed at 500 °C for 2 h. Doses of 5%, 10% and 20% of BC were applied to the Pb soils contaminated (165.7 mg/kg), that were arranged in 2 kg pots except for the control sample, and Lactuca sativa was subsequently grown cultivated to evaluate the Pb availability. The results indicated an improvement in soil quality at higher BC dose, increase of 0.34 pH units, decrease of Pb extracted by EDTA (27% to 62% of decrease), and non-significant Pb content in leachates (< 1 mg Pb/L) and no detection in plant roots (< 0.01 mg/kg), except for the control plant (0.7 mg Pb/kg) in the original soil. A logarithmic relational model between BC dose and Pb adsorbed in the soil was obtained (R² = 0.9938, p < 0.05) showing that the decrease of Pb availability in the soil increased for higher BC doses, which represents an eco-friendly remediation alternative. It is recommended to investigate the interaction relationships between the soil quality parameters and to establish functional models of bioaccumulation and extractable metal of the amended soil. [ABSTRACT FROM AUTHOR]

Introduction: Beans are most widely cultivated legume in the world. In Mexico it is second most important crop after corn and of basic importance for human consumption. Selection of varieties tolerant to water deficit constitutes a strategy to increase the genetic stability of crops and reduce losses in yield in order to define specific agroecotypes for bean crop. Method: Objective of work was to evaluate four varieties of black beans with horizontal resistance to hydric stress under rainstorm conditions in acid soils in two localities of Northeastern Sierra of state of Puebla. A randomized complete block design with 10 treatments and 5 repetitions was used; variables evaluated were a) survival during phenological cycle of crop and b) potential yield with addition of agricultural lime to soil, during 2019 agricultural cycle. Results: The emergence of the crop was recorded 10 days after sowing (dds), flowering (60 dds) and physiological maturity at 124 dds, in San Juan Acateno of the municipality of Teziutlán and in Pezmatlán of the municipality of Tlatlauquitepec. The Huejonapan and Acatlán bean varieties without lime application, obtained the highest potential yield with 757 and 562 kg ha-1 respectively in the town of San Juan Acateno under rainstorm conditions during the 2019 agricultural cycle. Conclusion: Application of agricultural lime did not have a significant effect on yield of improved varieties, as well as in Michigan regional control; However, highest production was presented in Huejonapan and Acatlán variety without application of agricultural lime during 2019 agricultural production cycle for town of San Juan Acateno in municipality of Teziutlán, Puebla. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effects of the application of liquid lime on sorghum growth in an Ultisol. This research was conducted between August and November, 2011 at the Agricultural Research Center, San José, Costa Rica. In an Ultisol planted with sorghum, in pots of 800 ml, the following treatments where applied: control without lime, calcium carbonate at doses of 10 and 20 l/ha, magnesium oxide at doses of 10 and 20 l/ha, calcium carbonate + magnesium oxide at doses of 5 + 5 and 10 + 10 l/ha, respectively. Six weeks after planting, sorghum was harvested, measuring leaf area, dry and fresh weight of the aerial and root biomass, nutrient absorption and the soil chemical characteristics. Treatments using calcium carbonate and calcium carbonate + magnesium oxide obtained the best values of leaf area and the higher weight of the aerial and root biomass of sorghum. Even though there were no significant differences between liquid lime treatments, there were regarding control without lime and weight biomass variables. Liquid calcium carbonate significantly increased Ca absorption, and the calcium carbonate + magnesium oxide treatment at doses of 10 l/h showed the highest Mg absorption. All amendment treatments caused an improvement of the soil fertility, the most notable being the application of 20 l/ha of magnesium oxide that dropped the exchangeable acidity from 9.02 to 0.36 cmol(+)/l, acidity saturation dropped from 95 to 3.3%, and pH increased from 5 to 5.7. It was concluded that the liquid liming amendments had a positive effect over the crop and the soil fertility. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the neutralization power of amendments based on calcium and magnesium and to assess their effects on the cation exchange complex in soils of flat Pampas of Santa Fe. Three amendments (lime, dolomite and mixture amendment) at rates calculated to neutralize 100% and 150% of exchangeable hydrogen were applied to samples from soils incubated for 60 days. The responses on actual and potential pH, and hydrogen, calcium and magnesium exchangeables were assessed. The increment of actual pH showed differences between amendments and the order of response was lime > dolomite > mixture amendment. No difference between the applied rates were observed. The potential pH was more sensitive to the type and of rates amendment. All treatments reduced the level of unsaturation, although the full neutralization was not achieved with the tested rates. Increments of exchangeable calcium were observed in all treatments and the greatest calcium saturation was obtained when lime or mixture amendment were applied at the highest rate. Dolomite and mixture amendment significantly increased the content of magnesium regardless of the rate. The information presented here is useful for prescribing magnesic-calcareous amendments in soils of the flat Pampas of Santa Fe. [ABSTRACT FROM AUTHOR]