In comparison with other micronutrients, the levels of nickel (Ni) available in soils and plant tissues are very low, making quantification very difficult. The objective of this paper is to present optimized determination methods of Ni availability in soils by extractants and total content in plant tissues for routine commercial laboratory analyses. Samples of natural and agricultural soils were processed and analyzed by Mehlich-1 extraction and by DTPA. To quantify Ni in the plant tissues, samples were digested with nitric […]

In this study available cooper (Cu) content in different sources of this micronutrient was determined using several extractants. The cooper sources were: coppper oxide p.a. + copper powder p.a., copper oxide 40 Ind., CuSO4.5H2O p.a., chalcopyrite ore, copper powder p.a. and copper oxide p.a., and they were used in the following extraction procedures: total Cu content and soluble Cu contents in water, citric acid at 20 g L-1, neutral ammonium citrate (1 + 9) and DTPA at 0.005 mol L-1. […]

The characterization of several soil phosphorus (P) pools allowed the evaluation of P components not usually monitored in fertilizer soil tests and can help to understand this nutrient’s cycle. The aim of this study was to evaluate the changes in P pools of a Fluventic Eutrochrepts fine clay which had been under long-time sugarcane plantation. In one situation the sugarcane had been cropped for 55 years with and without trash burning prior to harvesting. The other sugarcane plantation, cultivated for 35 years, […]

The knowledge of the dynamics of the organic N compound mineralization in the soil is important for the efficient use of N in agricultural production systems. With the objective of evaluating the protease activity and its relations to the contents of different N forms in a Dark Red Latosol cultivated with orange trees, soil samples were collected from two depths (0-10 and 10-20 cm) under top projection and between rows in the months of November and December 1998 and February and […]

In addition to improving chemical attributes of the soil, such as pH, exchangeable Ca and available Si, calcium silicate fertilization in soils with low soluble silicon (Si) can also affect rice yield due to a greater resistance to lodging and increased photosynthetic area. The objective of this study was to evaluate Si availability in soils from the Brazilian savannas (Cerrado). The experiment was carried out in a greenhouse using upland rice. The treatments consisted of 5 Si rates (0, 120, […]

The suitability of four extraction methods (acetic acid 0.5 mol L-1, buffer pH 4.0, calcium chloride 0.0025 mol L-1 and water) for estimating the amount of available Si in soil for upland rice was determined. Four soil types corresponding to the following classes were used: Typic Acrustox – isohyperthermic (LEa), Typic Acrustox – isohyperthermic (LVa), Rhodic Acrustox – isohyperthermic (LRd) and Ustoxic Quartzipsammentic – isohyperthermic (AQa), all of them from the Triângulo Mineiro region in Minas Gerais, Brazil. Five Si levels were created in each […]

Total and soluble boron contents were evailable by means of three extractors, used as plant availability indexes, in order to study their relationships with soil properties in representative mapping units of the state of Ceará, Brazil. Composite soil samples from the surface soil layers (0-20 cm) of Quartz Sands (AQd), Alluvium (Ae), Planosol (PL), Bruno non Calcic (NC), Cambisol (Ce), Red-Yellow Podzol (PV), Red-Yellow Latosol (LV) and Littosol (Re) were used. Total boron was determined after fusion with sodium carbonate […]

Information about availability of boron in the Brazilian semi-arid soils is scarce. A greenhouse assay was conducted with 29 superficial samples (0-20 cm) obtained from representative mapped soils of the State of Ceará, Brazil, using sunflower as an indicator. The experiment was performed in 2.5 kg pots containing soil, fertilized with two boron levels (0 and 1.5 mg kg-1) with three replicates per treatment. The boron availability in the soil was determined by hot water, 0.05 mol L-1 hydrochloric acid […]

Nitrogen mineralization potential (No) for ten Rio Grande do Sul, Brazil, soils was studied with corn grown on 20 kg pots for 45 days, as compared with nitrogen mineralized in aerobic incubation for 32 weeks. No values ranged from 108.6 to 210.8 mg kg-1, being similar to the total nitrogen mineralized. Mineralization velocity was higher during the first four weeks, and overall mineralization rate varied from 0.2985 to 0.3181 week-1 among soils. The correlation coefficient between corn absorbed nitrogen and […]