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Soil compost application is a common soil management practice used by small farmers of Central-South Chile that produces positive effects on soil properties and also promotes presence and activity of arbuscular mycorrhizal fungi (AMF). This fungi form symbiosis with plant roots improving plant nutrition, as well as producing glomalin, a glycoprotein that has been associated with soil aggregation stability. Therefore, the aim of this study was to evaluate, in an Ultisol from Central-South Chile, the effect of different doses of compost on some soil characteristics at the end of the third year of a crop sequence including wheat (Triticum aestivum L.), bean (Phaseolus vulgaris L.), and grassland (Lolium multiflorum Lam. associated with Trifolium repens L.). Studied soil characteristics included chemical (pH, available-P, organic C), biological (C and N biomass, AMF spore number, root colonization percentage, mycelium length, and glomalin content), as well as physical parameters (water holding capacity [WHC], and water stable aggregates [WSA]). Results showed that, in general, compost application increased soil pH, mycorrizal roots, mycelium length, glomalin levels, and WSA. Significant relationships were found between C and N biomass, C biomass and WSA, C biomass and glomalin, WSA and WHC, among others. Results suggest that compost application to this type of soil is a feasible option as a fertilizer substitute, and a way to avoid soil erosion by small local farmers involved in organic agriculture.

EVALUATION OF THE USE OF CHEMOMETRIC METHODS IN SOIL ANALYSIS. One of the major interests in soil analysis is the evaluation of its chemical, physical and biological parameters, which are indicators of soil quality (the most important is the organic matter).Besides there is a great interest in the study of humic substances and on the assessment of pollutants, such as pesticides and heavy metals, in soils. Chemometrics is a powerful tool to deal with these problems and can help soil researchers to extract much more information from their data. In spite of this, the presence of these kinds of strategies in the literature has obtained projection only recently. The utilization of chemometric methods in soil analysis is evaluated in this article. The applications will be divided in four parts (with emphasis in the first two): (i) descriptive and exploratory methods based on Principal Component Analysis (PCA); (ii) multivariate calibration methods (MLR, PCR and PLS); (iii) methods such as Evolving Factor Analysis and SIMPLISMA; and (iv) artificial intelligence methods, such as Artificial Neural Networks.Keywords: chemometrics; soil analysis; principal component analysis. DIVULGAÇÃO INTRODUÇÃOCom a crescente sofisticação das técnicas instrumentais de análise química, impulsionada pela invasão de microprocessadores e microcomputadores no laboratório, técnicas de tratamentos de dados mais complexas do ponto de vista matemáti-co e estatístico tornaram-se necessárias 1 . A análise de dados é uma parte essencial em todo experimento, sendo univariada quando somente uma variável é medida sistematicamente para várias amostras. Há muito tempo a estatística univariada vem sendo aplicada a problemas químicos, mas a sua utilização tornou-se limitada. Nas últimas décadas, a aná-lise multivariada foi introduzida no tratamento de dados quími-cos, ganhando rapidamente popularidade e dando origem a uma nova disciplina, batizada de Quimiometria. O modelo estatístico dos métodos multivariados considera a correlação entre muitas variáveis analisadas simultaneamente, permitindo a extração de uma quantidade muito maior de informação.Neste artigo será avaliada a utilização de métodos quimiométricos em análise de solos. O solo é uma estrutura complexa formada pela influência de fatores geológicos, topográficos, climáticos, temporais e antropogênicos; sendo a parte mais importante da geosfera e de onde provêm a maior parte dos nossos alimentos. Além disso, ele funciona como uma espécie de filtro ambiental para a purificação da água e do ar 2 . O interesse maior na análise de solos está na avaliação de seus parâmetros químicos (concentração de metais e nutrientes, pH, etc.), físicos (compactação, umidade, etc.) e biológicos (microrganismos, etc.), os quais são um indicador de sua qualidade. Dentre os constituintes do solo, o mais estudado é a matéria orgânica (MO). Esta controla muitas de suas propriedades e é um fator central na manutenção de sistemas agrícolas sustentá-veis. Práticas que favoreçam a conservação da MO melhoram as propriedades ...

SUMMARYProperties of a claim loam soil, collected in Aranjuez (Madrid) and enriched with organic matter and microorganisms, were evaluated under controlled temperature and moisture conditions, over a period of three months. The following treatments were carried out: soil (control); soil + 50 t ha -1 of animal manure (E50); soil + 50 t ha -1 of animal manure + 30 L ha -1 of effective microorganisms (E50EM); soil + 30 t ha -1 of the combination of various green crop residues and weeds (RC30) and soil + 30 t ha -1 of the combination of various green crop residues and weeds + 30 L ha -1 of effective microorganisms (RC30EM). Soil samples were taken before and after incubation and their physical, chemical, and microbiological parameters analyzed. Significant increase was observed in the production of exopolysaccharides and basic phosphatase and esterase enzyme activities in the treatments E50EM and RC30EM, in correlation with the humification of organic matter, water retention at field capacity, and the cationic exchange capacity (CEC) of the same treatments. The conclusion was drawn that the incorporation of a mixture of effective microorganisms (EM) intensified the biological soil activity and improved physical and chemical soil properties, contributing to a quick humification of fresh organic matter. These findings were illustrated by the microbiological activities of exopolysaccharides and by alkaline phosphatase and esterase enzymes, which can be used as early and integrated soil health indicators.Index terms: quality indicators, microorganisms, physical, chemical, and biochemical soil properties.(