Diagnosis and correction of soil nutrient limitations in intensively managed Southern pine forests. Quarterly report for the period January-March 2000

This report is a summary of project status and activities performed during the quarter: (1) Initial error runs were finished and coding was adjusted to account for errors. A documentation manual and users manual have been written and gone through the first editing. The model was presented to the forest industry during a review meeting and adjustments were made to the model based on their input. The model has been sent to interested parties in Canada and Australia to test it and report back on any errors or modifications they feel would be necessary. (2) Based on the laboratory studies, one paper was written and submitted to the Soil and Water Science for internal review. It is currently under internal review. This paper describes a method for measuring resorption isotherms. A second paper that uses this method to investigate desorption isotherms for different soils is in progress. (3) All soil samples have been dried and sieved. All tissue samples have been ground and the ashing of the tissue samples has just begun. (4) A literature search continued focusing on root to shoot relationships of fast growing pine in order to assist the development of the nutrient demand section of the model. This is about 40% done

Cacao Quality: Highlighting Selected Attributes

World demand for cacao and the requirements for quality beans have increased every year. Research studies have developed standards for aspects of cacao quality that meet industrial criteria as well as international import and export legislation that is aimed at food security. This review focused on selected attributes of cacao bean quality. These attributes include the amount of acids, simple carbohydrates, proteins, amino acids, lipids, phenolic substances, and methylxanthines. Other attributes are bean moisture content, quantity of mineral nutrients, and presence of potentially toxic elements. Microbiological and organoleptic attributes are also of interest. Future research on cacao quality should focus on bean sampling, geographical location of plantations, genetic diversity of the cacao material, and standardized analytical methods for determination of organic and mineral substances. © 2017 Taylor & Francis.33438240

Formas de fósforo no solo sob leguminosas florestais, floresta secundária e pastagem no Norte Fluminense Soil phosphorus forms under leguminous tree species, secondary forest and pasture in Northern Rio de Janeiro State, Brazil

Em solos muito intemperizados, a disponibilidade de P para as plantas está estreitamente associada às formas de P orgânico, que tem o seu conteúdo alterado por influência do tipo de cobertura vegetal. O objetivo deste trabalho foi estimar os teores de fósforo de compostos orgânicos (Po-total, Po lábil e P microbiano do solo), em plantios de Acacia auriculiformis (acácia) e Mimosa caesalpiniifolia (sabiá), em floresta secundária e em pastagem. Os teores médios ponderados de Po total e Po lábil, pelo teor de argila, foram de 375 mg kg-1 de P na argila e de 40,2 mg kg-1 de P na argila, respectivamente. Os solos sob acácia e sabiá apresentaram maior teor relativo de Po (total e lábil) do que os solos sob pastagem e capoeira. O Po representou de 22,6 a 39,6 % do P total extraído dos solos das coberturas estudadas. Em relação ao P lábil total, o Po lábil representou, em média, 67,1 %. Para o P microbiano, o maior teor foi encontrado no solo sob sabiá, seguido da floresta secundária, acácia e pastagem. Contudo, foi na capoeira que houve a maior eficiência da biomassa microbiana do solo em imobilizar P. O teor de P disponível por Mehlich-1 correlacionou-se positivamente com o teor de C e o de P da biomassa microbiana. Houve estreita correlação positiva entre o P microbiano e o C microbiano.<br>In highly weathered tropical soils phosphorus (P) bioavailability to plants is closely associated with soil organic P forms, which in turn are influenced by the vegetation cover. The aim of this study was to evaluate total organic P (Po), labile P fractions and microbial biomass P in soils under Acacia auriculiformis and Mimosa caesalpiniifolia stands, secondary forest and pasture. The clay-adjusted average content of total Po and labile Po were 375 mg kg-1 P and 40.2 mg kg-1, respectively. The Po contents (total and labile) in soils under Acacia auriculiformis and Mimosa caesalpiniifolia were higher than under pasture and secondary forest soils. The proportion of Po ranged from 22.6 to 39.6 % of total extracted P in soils under the vegetation cover types studied. The labile Po represented about 67.1 % of total labile P. The greatest amount of soil microbial biomass P (MBP) was observed under Mimosa caesalpiniifolia, followed by secondary forest, Acacia auriculiformis and pasture. However, the soil microbial biomass of the secondary forest was the most efficient regarding P immobilization (MBP/total Po ratio). Available P was positively correlated with soil microbial biomass C and microbial P, and microbial P was positively related to microbial C