Knowledge about the proper management of not-burned sugar cane is still limited, particularly regarding nitrogen fertilization. A field experiment was carried out to evaluate sugar cane yield, the balance of 15N fertilizers in the soil-plant-residue system and ammonia loss by volatilization in sugarcane ratoon crop without straw burning prior to mechanical harvesting, comparing different locations of surface-applied nitrogen fertilizers. The sugar cane variety SP81-3250. Treatments were arranged in a complete randomized blocks, with four replicates. The treatments consisted of four […]

The traffic of agricultural machinery and soil compaction occur near the canopy of citrus trees, which increases soil physical restrictions to root growth. Soil management strategies include the use of permanent groundcover in the interrows of orange tree plantations, although the effects of these practices on the soil physical quality are largely unknown. The objective of this study was to assess the impact of groundcover management systems on some indicators of soil physical quality for orange tree orchards. The study […]

The focus of our study were to study soil-landscape relationships in a sandstone-basalt transition lithosequence and to compare the limits of geomorphic surfaces mapped in the field with those mapped by geostatistical techniques. An area of 530 ha was mapped using GPS equipment in order to generate a model of digital elevation, which allowed for the establishment of a transection of 2.100 m from the hill top downwards. Along the transection, the altitude was measured at 50 m regular intervals […]

The high organic matter content in sewage sludge is one of the reasons for its utilization as soil amendment. This study aimed to evaluate the effect of consecutive sewage sludge applications on the amounts of carbon, total and mineral nitrogen, pH, and bulk density in a Latossol. Two soil layers (0-0,1 and 0,2-0,4 m) were evaluated after three corn cultivations in Jaguariúna (São Paulo State, Brazil), between 1999 and 2001. The treatments consisted of three consecutive applications of two sewage […]

Responses of leaf senescence to P supply could constitute adaptive mechanisms for plant growth under P-limiting conditions. The aim of this study was to evaluate the effects of soil P supply on leaf senescence of common bean (Phaseolus vulgaris L.). Eight P levels, ranging from 5 to 640 mg kg-1 P, were applied to pots containing four bean plants of cultivar Carioca in 10 kg of an Oxic Haplustult soil. Attached leaves were counted weekly, abscised leaves were collected every […]

According to the system conditions, humic acids act as oxidants or as reductants. In natural systems the electron flow is directly associated with humus content and quality. Electrode potential and oxidation capacity inform about the intensity and capacity of the redox systems. In previous studies it has been assumed that free radicals participate in humic acid redox reactions. In our study six humic acids isolated from composed organic residues were titrated with an oxidant (I2) in inert atmosphere and specified […]

Nitrogen is indispensable for pasture establishment, maintenance and production recovery, and its effect is apparently dependent on sulphur supply. It was hypothesized that increasing nitrogen supply requires higher sulphur rates to recover signalgrass (Brachiaria decumbens Stapf.), and that fertilization increases the water use efficiency by plants. The leaf area, dry matter yield, water consumption, and water use efficiency of the grass were evaluated under the application of nitrogen and sulphur rates. Cylinders of 15 cm diameter and 20 cm depth […]

The search for methods to determine the content of soil organic matter (SOM) that do not generate hazardous waste is important. SOM oxidation with dichromate is used in most Brazilian soil laboratories and it generates chromium-contaminated waste. The objective of this study was to evaluate the weight loss-on-ignition (LOI) method in comparison to the wet digestion procedure based on sulfuric acid-chromium solution as commonly used in soil analysis laboratories of Rio Grande do Sul (RS) and Santa Catarina (SC) states, […]

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. […]

Knowledge on mineral nutrient dynamics in coffee trees is important to identify the period of greatest nutritional requirement by the plant, allowing the improvement of fertilization techniques. The aim of our research was to study Ca and Mg dynamics in coffee fruits from anthesis to maturation and compare it with the dynamics of the same elements in leaves of productive branch leaves. The experiment was carried out with three Arabic coffee varieties (Catuaí Vermelho IAC-99, Rubi MG-1192 and Acaiá IAC-474-19) […]