Phosphorus sources residual effects on tifton 85 production and nutritive value cultivated in a tropical weathered soil

Acid reactions and low available phosphorus in tropical soils limit forage yield. The aim was to evaluate soil chemical characteristics pH, P and Mg, forage nutritive values, critical soil and plant P levels and the residual effect of each source. The experiment was in a greenhouse with a Rhodic Haplustox, loam texture. Experimental design was a 5 x 4 factorial with five replicates which phosphate fertilizers were triple superphosphate, reactive rock phosphates Gafsa and Arad, and fused magnesium phosphate powder and coarse, applied at rates of 30, 60, 90 and 120 mg kg-1 P and a control treatment without P. The effectiveness of rock phosphates increased due to their residual effect. The coarse fused magnesium phosphate resulted in the lowest efficiency. The P critical level in soil and plant were 18 mg kg-1 and 2.4 g kg-1, respectively. The increase of phosphorus rates provided an increase in crude protein content

Nutrient Partitioning and Stoichiometry in Unburnt Sugarcane Ratoon at Varying Yield Levels

Citation: Leite, J. M., Ciampitti, I. A., Mariano, E., Vieira-Megda, M. X., & Trivelin, P. C. O. (2016). Nutrient Partitioning and Stoichiometry in Unburnt Sugarcane Ratoon at Varying Yield Levels. Frontiers in Plant Science, 7, 14. doi:10.3389/fpls.2016.00466Unraveling nutrient imbalances in contemporary agriculture is a research priority to improve whenever possible yield and nutrient use efficiency in sugarcane (Saccharum spp.) systems while minimizing the costs of cultivation (e.g., use of fertilizers) and environmental concerns. The main goal of this study was therefore to investigate biomass and nutrient [nitrogen (N), phosphorus (P), and potassium (K)] content, partitioning, stoichiometry and internal efficiencies in sugarcane ratoon at varying yield levels. Three sites were established on highly weathered tropical soils located in the Southeast region of Brazil. At all sites, seasonal biomass and nutrient uptake patterns were synthesized from four sampling times taken throughout the sugarcane ratoon season. In-season nutrient partitioning (in diverse plant components), internal efficiencies (yield to nutrient content ratio) and nutrient ratios (N:P and N:K) were determined at harvesting. Sugarcane exhibited three distinct phases of plant growth, as follows: lag, exponential linear, and stationary. Across sites, nutrient requirement per unit of yield was 1.4 kg N. 0.24 kg P, and 2.7 kg K per Mg of stalk produced, but nutrient removal varied with soil nutrient status (based on soil plus fertilizer nutrient supply) and crop demand (potential yield). Dry leaves had lower nutrient content (N, P, and K) and broader N:P and N:K ratios when compared with tops and stalks plant fractions. Greater sugarcane yield and narrowed N:P ratio (6:1) were verified for tops of sugarcane when increasing both N and P content. High-yielding sugarcane systems were related to higher nutrient content and more balanced N:P (6:1) and N:K (0.5:1) ratios

Eficiência agronômica de adubos nitrogenados em soqueira de cana‑de‑açúcar colhida sem queima

The objective of this work was to evaluate the agronomic efficiency of the nitrogen sources urea (U), ammonium nitrate (AN), ammonium sulfate (AS), and ammonium chloride (AC) on green harvesting sugarcane ratoon, as well as the residual effect of these sources on crop productivity in the subsequent crop year. A randomized block design was used with four replicates. Treatments consisted of applying 120 kg ha-1 of N fertilizer on a Typic Hapludox covered by straw residues resulting from the harvest without burning of the first ratoon. A control treatment was included with no N fertilizer. To evaluate the residual effect of the nitrogen fertilizers, 450 kg ha-1 of a 20‑5‑19 formulation was applied to soil after sugarcane ratoon harvest. The highest production of stalks and sugar, in the 2006/2007 season, was obtained with the source AS. In the 2007/2008 harvest season, no residual effect of N fertilization was observed and there was a productivity decrease in the AC treatment in comparison to the control. The AC source, at a dose of 120 kg ha-1 N in the fertilization of the second ratoon, is agronomically as efficient as the other N sources used, but shows less efficiency in the subsequent crop year.O objetivo deste trabalho foi avaliar a eficiência agronômica das fontes nitrogenadas ureia (U), nitrato de amônio (NA), sulfato de amônio (SA) e cloreto de amônio (CA) em soqueira de cana‑de‑açúcar colhida sem queima, bem como determinar o efeito residual dessas fontes sobre a produtividade da cultura no ano agrícola subsequente. Utilizou-se o delineamento experimental de blocos ao acaso, com quatro repetições. Os tratamentos consistiram da aplicação de 120 kg ha-1 de N a um Latossolo Vermelho distrófico, coberto por palhada resultante da colheita sem queima da primeira soqueira. Incluiu-se um tratamento de controle sem adição de N fertilizante. Para avaliar o efeito residual dos adubos nitrogenados, aplicaram-se 450 kg ha-1 do formulado 20‑5‑19 após o corte da cana‑soca. A maior produção de colmos e de açúcar na safra 2006/2007 foi obtida com a fonte SA. Na safra 2007/2008, não foi verificado efeito residual da adubação nitrogenada e houve queda de produtividade do tratamento CA em comparação ao controle. A fonte CA, à dose de 120 kg ha-1 de N em adubação de soqueira de segundo corte, é agronomicamente tão eficiente quanto as demais fontes de N utilizadas, mas tem menor eficiência no ano agrícola subsequente

Agronomic efficiency of nitrogen fertilizers on green harvesting sugarcane ratoon

O objetivo deste trabalho foi avaliar a eficiência agronômica das fontes nitrogenadas ureia (U), nitrato de amônio (NA), sulfato de amônio (SA) e cloreto de amônio (CA) em soqueira de cana-de-açúcar colhida sem queima, bem como determinar o efeito residual dessas fontes sobre a produtividade da cultura no ano agrícola subsequente. Utilizou-se o delineamento experimental de blocos ao acaso, com quatro repetições. Os tratamentos consistiram da aplicação de 120 kg ha-1 de N a um Latossolo Vermelho distrófico, coberto por palhada resultante da colheita sem queima da primeira soqueira. Incluiu-se um tratamento de controle sem adição de N fertilizante. Para avaliar o efeito residual dos adubos nitrogenados, aplicaram-se 450 kg ha-1 do formulado 20-5-19 após o corte da cana-soca. A maior produção de colmos e de açúcar na safra 2006/2007 foi obtida com a fonte SA. Na safra 2007/2008, não foi verificado efeito residual da adubação nitrogenada e houve queda de produtividade do tratamento CA em comparação ao controle. A fonte CA, à dose de 120 kg ha-1 de N em adubação de soqueira de segundo corte, é agronomicamente tão eficiente quanto as demais fontes de N utilizadas, mas tem menor eficiência no ano agrícola subsequente

Biochar as a soil conditioner for common bean plants

Biochar is a carbon-rich material produced during organic waste pyrolysis. In this context, two experiments were performed to evaluate the effect of biochar produced from rice husks and cattle manure on soil fertility and common bean production, as well as to identify the optimal dose of cattle manure biochar to be applied. The first experiment (Experiment I) was conducted according to a completely randomized design (factorial scheme 2 × 2 × 2 + 1) with six replicates: two types of biochar (cattle manure biochar and rice husk biochar), with and without acidity correction [addition of calcium carbonate and magnesium carbonate (PA) in a proportion of 4:1 (Ca:Mg) to raise the soil base saturation to 60%], with or without the addition of 120 mg dm-3 of phosphorus (P) as ammonium phosphate, and a control treatment (without biochar, acidity correction, and P). Based on the results of Experiment I, a second experiment was conducted according to a completely randomized design, with five treatments (doses of biochar from cattle manure) and four replications. Rice husk biochar, as a conditioner of soil chemical properties, had less prominent effects than cattle manure biochar. Cattle manure biochar functioned as a corrective for soil acidity and a source of nutrients (mainly phosphorus). The dose corresponding to 5.46% of the soil volume led to the maximum grain production by common bean plants