The degree of soil nutrient availability to plants is one of the major factors determining crop production. Mathematical models have been proposed to simulate nutrient flux toward roots, taking into account several physical and chemical soil parameters as well as anatomical and physiological root traits. The objective of this paper was to establish a relationship between Baldwin’s theoretical diffusion model and experimental field data involving the response of wheat to K fertilization. Based on simulations with the theoretical model, it […]

Soil fertility levels in the Agreste region, state of Paraíba, Brazil are generally low. Usually, animal manure is applied to soils to supply agricultural crops with nutrients. However, depending on the quality of the manure applied, incorporation can lead to soil nitrogen immobilization in the beginning of the growing season. It was hypothesized that planting and incorporating crotalaria (Crotalaria juncea) together with animal manure could synchronize the nutrient mineralization pattern more specifically with crop demand. In 2003, field and green-house […]

Potato (Solanum tuberosum L.) is an important cash crop in the semi-arid region of Paraíba, Brazil. However, potato productivity is limited by low soil fertility and the limited and highly variable precipitation pattern of this region. Animal manure is the main nutrient source for soil fertility amelioration, but farm manure available is usually not enough to fertilize crops. A cover crop could decrease the demand for animal manure. The characteristics of Crotalaria (Crotalaria juncea L.) recommend it as green manure. […]

Applying lime on the soil surface in soils managed under no-tillage has caused an excess of basic cations in the most superficial layers of the soil profile. On the other hand, subsoil acidity is considered a constraint to the development of deep plant roots. The objective of this study was to evaluate Ca2+, Mg2+, NO3– and SO42- leaching in the soil profile as affected by liming and top dressing nitrogen fertilization in cotton, grown with straw cover on the soil […]

In no-tillage systems lime is applied on the soil surface to avoid soil mobilization. Nitrogen fertilization adds anions that can increase the solubility of basic cations of the soil due to formation of ionic pairs. The objective of this study was to characterize the dynamics of anions (SO42- and NO3–) and cations (NH4+, Ca2+, Mg2+ and K+) in the soil solution, and the nutrient uptake by cotton plants subjected to different lime application forms and ammonium sulfate fertilization, with straw […]

In pastures, the evaluation of fertilization efficiency of urea-N is important since it is applied on a massive scale. Several studies report an enhancement of the fertilizer’s efficiency by associated applications of urea with potassium chloride (KCl) and ordinary superphosphate (OSP). In the recovery of degraded pastures or in intensive exploration systems, high quantities of KCl and OSP used as corrective fertilization are applied at the november, beginning of the rain season. Split applications of KCl and OSP could easily […]

Two field experiments were conducted on two experimental EPAMIG Farms (Minas Gerias State), in order to evaluate the nutritional coffee status by the nutritional balance index (NBI) supplied by DRIS in response to potassium fertilization. The experimental design was a split plot scheme of randomized blocks, carried out on a Red Latosol distroferric (RLdf) of São Sebastião do Paraíso and a Yellow Red Latosol distrofic (YRLd) of Patrocínio. Three K sources were applied in the plots: potassium chloride (KCl), potassium […]

To evaluate residual effects of potassium fertilization throught ryegrass on subsequent rice, under no-tillage system, a field experiment was performed from May 1996 to April 1997 in the Agricultural Center (Centro Agropecuário) of Palma/UFPel, in the county of Capão do Leão, Rio Grande do Sul State, Brazil. The examined soil was a Planossolo (Albaqualf) belonging to the Pelotas mapping unit. Treatments consisted of three K levels applied on the ryegrass (0, 0.5 and 1 time the recommended dose of 70 […]

A field experiment was conducted in the state of Paraná, Brazil, to evaluate the effect of liming on soil acidity, soil nutrient availability and yields of maize and soybeans on a Red Latosol (Oxysol), which had been cultivated for three, six and nine years under no-tillage (NT). Lime was broadcasted to the soil surface in four rates- 0, 33.3, 66.7 and 100% of the amount calculated to increase the soil base saturation (V%) to 70%; an additional treatment consisted of […]

Planting spacings and sowing dates may influence nutrient absorption. Therefore, a field experiment was carried out from 1991 to 1992, at the experimental station of Embrapa/Soil Research National Center, located in Senador Canedo, Goiás, Brazil, to determine the N, P and K uptake levels in the aerial part of sunhemp (Crotalaria juncea), Crotalaria ochroleuca, black velvet bean (Mucuna aterrima) and pigeonpea cv. Kaki (Cajanus cajan), under three sowing times (beginning, middle and end of the growing season) and two spacings […]