Dário Costa Primo

Evaluation of the nutritional quality of organic compost produced with tobacco residues

The use of agroindustrial waste to produce organic compost can result in greater sustainability for agricultural systems. This study aimed to analyze the final quality of the organic compost, according to their nutrients and the presence of active toxic substances. The combinations of ground tobacco stem, bovine manure and rumen (TF+EB+RB), tobacco stem, cattle manure and Microsept Dust (TF+EB+MP) and tobacco stem and cattle manure (TF+EB) were evaluated. Mean samples of each compost were analyzed to determine the concentration of micro and macro nutrients at 60 and 120 days and to verify the nicotine concentration and the presence or absence of pesticide residues in the raw material (TF) and in the composts obtained at 120 days. The data obtained showed high concentrations of potassium (K), nitrogen (N), chloride (Cl) and iron (Fe) in the final compost compared to the other micro and macro nutrients. Neither pesticides in the raw material (TF), nor presence of nicotine in the mean samples obtained within 120 days was detected, demonstrating the absence of environmental impact risks in the agricultural use of these composts. At the end of the composting process, the mixture TF+EB was the one which resulted in an organic compost with the highest concentration in micro and macro nutrients.

Grain productivity and nitrogen fractions of maize under organic fertilization in semiarid region Brazil.

Visou-se avaliar, neste trabalho, a aplicacao de adubos orgânicos sobre as fracoes nitrogenadas e a sua relacao com a produtividade do milho na regiao semiarida. O milho foi cultivado em um Neossolo Fluvico em parcelas distribuidas em blocos ao acaso com quatro repeticoes e oito tratamentos arranjados em esquema fatorial (2 x 3) + 2, incluindo dois metodos de aplicacao dos adubos (incorporado ou em superficie) e quatro tipos de adubacao (15 t.ha-1 de biomassa de gliricidia, 15 t.ha-1 de biomassa de marmeleiro, 15 t.ha-1 de esterco) e parcelas controle sem adubacao. Os adubos orgânicos e os modos de aplicacao ao solo influenciaram de forma diferente a produtividade de graos e a nutricao do milho. Os tres tipos de adubos, quando aplicados em superficie, incrementaram produtividade de graos e os teores de N nos graos. O teor maior de N foliar foi maior na gliricidia em superficie. O teor de N soluvel foliar incrementou com o controle e marmeleiro incorporados e gliricidia aplicada em superficie. O esterco em superficie incrementou o teor de P foliar, enquanto o K com o marmeleiro incorporado ao solo. As fracoes nitrogenadas no tecido foliar nao acompanharam a tendencia da produtividade de graos, ou seja, os tratamentos que proporcionaram as maiores produtividades de graos apresentaram as menores fracoes nitrogenadas.

Timing and placement of cattle manure and/or gliricidia affects cotton and sunflower nutrient accumulation and biomass productivity

Organic fertilizers are a viable alternative to increase oilseed productivity in family agriculture systems. The study aimed to evaluate the effects of timing and placement of cattle manure and/or gliricidia (Gliricidia sepium Jacq. Walp) prunings on cotton (Gossipium hirsutum L.) and sunflower (Helianthus annuus L.) nutrient accumulation and biomass productivity. Experiments were carried out in 2010 and 2011 in Taperoá, Paraíba, Brazil. The organic fertilization treatments were: GI - gliricidia incorporated before planting; GS - gliricidia applied on surface 45 days after planting (DAP); MI + GI - manure and gliricidia incorporated before planting; MI + GS - manure incorporated before planting and gliricídia applied on the surface 45 DAP; MI - manure incorporated before planting; and T - with no organic fertilization. In 2010, treatment MI + GS increased N, P, and K accumulation in cotton (12 and 7 kg ha-1) as well as in sunflower (20 and 29 kg ha-1). In 2011, GI and GS treatments resulted in higher N, P, K accumulations in both crops. The highest cotton productivity in 2010 was obtained with MI + GS treatment (198 kg ha-1) and in 2011 with GS treatment (594 kg ha-1). For sunflower, MI + GS treatment yielded the highest productivity in 2010 (466 kg ha-1) and GI treatment in 2011 (3542 kg ha-1). GI and MI + GS treatments increased total biomass productivity for cotton and sunflower. The treatment that combined both cattle manure incorporated into the soil before planting and gliricidia applied on the surface 45 days after planting was the most viable management strategy.

Characterisation of soil organic matter in a semi-arid fluvic Entisol fertilised with cattle manure and/or gliricidia by spectroscopic methods

The stable fraction of soil organic matter (SOM) has received considerable attention due to concerns about the sustainability of agricultural systems. The main structural characteristics of the SOM of an Entisol in the semi-arid region of Paraiba state, Brazil, after 6 years of cultivation of annual crops with different organic fertiliser treatments, were determined. Six different treatments were evaluated, as follows: (1) gliricidia prunings (Gliricidia sepium Jacq. Walp) incorporated into the soil before planting (GI); (2) cattle manure incorporated before planting (MI); (3) gliricidia applied after planting (GS); (4) manure and gliricidia incorporated before planting (MI+GI); (5) manure incorporated before planting and gliricidia applied after planting (MI+GS); and (6) a control treatment. Spectroscopic techniques were used to analyse carbon in whole soil samples (0–20cm), as well as in fulvic acid (FA) and humic acid (HA) extracts. Surface-applied gliricidia resulted in the highest SOM content. Laser-induced fluorescence spectroscopy showed that MI+GS contributed to increases in the degree of humification, whereas for the HA fraction, the highest degree of humification occurred with the GS treatment. The ultraviolet–visible absorbance spectra of FA fractions indicated the presence of fresh soluble SOM in all treatments except GS, and mid-infrared region spectra revealed no differences in the chemical structure of the HA fractions. Application of gliricidia prunings (GI and GS), which are nitrogen rich and highly labile, resulted in low HA transformations compared with the control based on nuclear magnetic resonance analysis. Therefore, gliricidia, whether incorporated before planting or applied after planting, decreases the labile fractions of SOM, probably because of its higher decomposition rates.