Palavras-chave: Brassica oleracea var. botrytis, Brassica oleracea var. capitata, plantas de cobertura, ciclagem de nutrientes, produtividade. ABSTRACT Development and productivity of cauliflower and cabbage influenced by soil mulching typesThe use of cover crops preceding vegetable cultivation has been one option to reduce the necessity of mineral fertilizers. In this study we evaluated the soil covers applied preceding planting and its effects on some agronomic characteristics and productivity of cauliflower and cabbage. We used a factorial randomized blocks design, with four soil covers (sunnhemp, brachiaria, millet and fallow) and two crops (cauliflower and cabbage) with four replications in plots of 20 m 2 (4x5 m). We determined the number of leaves, height, head and stem diameter, and fresh and dry mass. Mulches influenced positively the agronomic characteristics of cauliflower and cabbage for head diameter (55.1 and 194.8 cm), stem diameter (70.4 and 49.2 mm) and horizontal diameter (169.9 and 14 8 mm), fresh mass (1.0 to 2.8 kg) and dry mass of the head (73.4 and 0.65 g) and productivity (7.3 to 19.2 t/ha) of the crops, respectively, when grown on brachiaria waste. The marketable fresh mass of cabbage (2.8 kg) was higher than the standard required by the Brazilian consumer market.

Soil management has a major effect on soil physical characteristics, and consequently on soil organic matter (SOM) content, which are important for the success of crop production. The aim of this study was to evaluate the soil physical attributes and the accumulation of SOM in no-tillage systems (NTS) with different periods of implantation in a conventional tillage area and to compare them with native forest (NF) in the Cerrado biome. The experiment was planned in a 3 × 4 factorial scheme, consisting of three soil treatments (NTS for 17 years (NTS17), NTS for 5 years (NTS5) and NF) and four soil depths (0–0.1, 0.1–0.2, 0.2–0.3 and 0.3–0.4 m), with a completely randomised design and four replicates. At deep soil layers (0.2–0.4 m) the NTS17 area had a greater soil density than the NTS5 and NF areas, and greater SOM compared with the NTS5 area. Soil macroporosity in the NTS5 area was below 10% at all soil depths evaluated. The NF area had the greatest total organic carbon content (1.39 dag kg–1), stock of carbon (16.63 Mg ha--1), amount of soil organic matter (28.66 Mg ha--1) and equivalent carbon credits (60.96 Mg ha–1). Carbon stocks were similar in the NTS areas in all soil depths evaluated. The results indicate that conventional tillage areas can be successfully recovered under the Cerrado edaphoclimatic conditions with the implantation of an NTS.

No abstract

Modelling of Soil Penetration reSiStance for an oxiSol... 89 r. Bras. ci. Solo, 36:89-95, 2012 Modelling of Soil Penetration reSiStance for an oxiSol under no-tillage (1) João tavares filho (2) , clarissa tieme Matsuda feltran (3) , José francirlei de oliveira (3) & edinei de almeida (3) SuMMary Soil penetration resistance is an important property that affects root growth and elongation and water movement in the soil. Since no-till systems tend to increase organic matter in the soil, the purpose of this study was to evaluate the efficiency with which soil penetration resistance is estimated using a proposed model based on moisture content, density and organic matter content in an oxisol containing 665, 221 and 114 g kg-1 of clay, silt and sand respectively under annual no-till cropping, located in londrina, Paraná State, Brazil. Penetration resistance was evaluated at random locations continually from May 2008 to february 2011, using an impact penetrometer to obtain a total of 960 replications. for the measurements, soil was sampled at depths of 0 to 20 cm to determine gravimetric moisture (g), bulk density (d) and organic matter content (M). the penetration resistance curve (Pr) was adjusted using two non-linear models (Pr = a d b g c and Pr' = a d b g c M d), where a, b, c and d are coefficients of the adjusted model. it was found that the model that included M was the most efficient for estimating Pr, explaining 91 % of Pr variability, compared to 82 % of the other model. index terms: no-till, compaction, physical properties, organic matter.

The objective of this study was to evaluate the residual concentration from the application of levels of phosphorus contained in an organomineral fertilizer (OMF) in two soils cultivated with cabbage and lettuce in succession. In randomized blocks, five doses of OMF were used as a source of P in Oxisol (0, 50, 100, 200, and 300% of the P dose was recommended for cabbage crop using OMF), plus an additional treatment (100% mineral). The doses applied to the Entisol were as follows: 0, 50, 100, 200, and 300% of the recommended P dose with OMF for cabbage crop, plus an additional treatment (100% mineral), with four repetitions. The production of fresh matter (FM) and dry matter (DM), the nutritional status of the cabbage and lettuce, and the residual effect of nutrients in the soil were also evaluated. The P concentration in the soil increased (p ≤ 0.05) with higher doses of OMF in the Oxisol in the two cycles evaluated. However, this occurred only in the first cycle in the Entisol. Using the 50% dose of OMF in the cabbage in both soils provided FM and DM production values that were at least 11% higher than those attained with mineral fertilizer.

The period of implantation of the no-tillage system (NTS) is a fundamental factor to the dimension of the changes that occur to the soil's physical, chemical and biological attributes. Thus, the objective of this study was to evaluate the soil changes to the physical attributes and correlate the results to the soil organic matter in areas of different long-term soil management. The study was set as a completely randomised design, in a 4 × 4 factorial scheme, with four management systems [5 years NTS (NTS5); 17 years NTS (NTS17); conventional tillage system for 20 years (CTS20); native area (NA)], and four soil depths (0-0.05, 0.05-0.1, 0.1-0.2, 0.2-0.4 m), with five repetitions. Soil mechanical resistance to root penetration (RP), bulk density (SD), volumetric moisture (VM), macro (Ma), microporosity (Mi) and total porosity (TP), and the aggregation parameters were evaluated. The CTS20, NTS5 and NTS17 presented superior SD in the most superficial soil layers, which was not yet causing resistance to root development. The SD was the only physical attribute that correlated significantly with all the other soil attributes evaluated, indicating the importance of such attribute to evaluate soil quality to crops. The soil physical attributes found in the Cerrado native area followed the sequence of similarities: no-tillage system with 17 years (most similar), with five years and the conventional tillage system (less similar). The changes caused by the anthropic activity in the soil's physical attributes are more pronounced and perceptible in soil depths up to 0.2 m.

The objective of this study was to evaluate the influence of different sources and doses of organic and mineral fertilization on the production of green-leaf lettuce. The experiment design used randomized blocks in a factorial scheme (6×3), with six doses of fertilizers (1 = 0; 2 = 25; 3 = 50; 4 = 100; 5 = 150, and 6 = 200% of the recommended fertilization for green-leaf lettuce crop) and three sources of fertilizers [cattle manure (CaM) and chicken manure (ChM), decomposed, on a wet basis and applied 100% at planting at the doses: CaM – 0, 12.5, 25, 50, 75, 100 Mg ha-1; ChM – 0, 5, 10, 20, 30, 40 Mg ha-1; mineral fertilization (MF) varying the N levels: 0, 37.5, 75, 150, 225, 300 kg ha-1 plus 400 kg ha-1 of P2O5 and 60 kg ha-1 of K2O]. The fertilization with CaM and ChM was more efficient than the MF at increasing the production of green-leaf lettuce, mainly because of  the higher residual effects of P in the Oxisol. The ChM provided a higher soil pH, P and K, while the CaM provided a higher soil Mg, organic carbon and organic matter. The dose with 144% of organic fertilization exclusively on a wet basis corresponding to 72 Mg ha-1 of CaM and 29 Mg ha-1 of ChM resulted in the highest green-leaf lettuce yield.

Cauliflower and cabbage require high amounts of nutrients in short periods of time; however, the intensive use of inorganic fertilizers can cause nutritional imbalances in these crops and reduce the quality of the final product. This study evaluated the chemical composition and yield of no-till cauliflower and cabbage grown on residues of various cover crops in Uberaba, Minas Gerais State, Brazil. The experimental design was randomized blocks with four cover crops (sunn hemp, brachiaria, pearl millet and fallow) and two main crops (cauliflower and cabbage). The treatments were evaluated on plots of 20 m2 with four replications. The following traits were analyzed after harvest: moisture (MO), ash (ASH), lipid (LIP), crude fiber (CF), protein (PTN), carbohydrates (CARB), total soluble solids (TSS), total titratable acidity (TTA), pH, ascorbic acid (AA), head fresh weight (HFW), head dry weight (HDW) and yield. Cauliflower cultivated on sunn hemp residues produced high levels of LIP, PTN, CARB, TSS and TTA, whereas cauliflower cultivated on brachiaria and millet residues demonstrated high AA levels when compared to the treatment with sunn hemp residues. In the aerial part, cabbage presented significantly higher levels of CARB, TTA and AA when cultivated on brachiaria residues, whereas PTN levels were higher on sunn hemp residues. The cultivation of cauliflower and cabbage on cover crop residues affected positively most of the chemical attributes of the evaluated crops when compared to the fallow treatment, although the highest yield and AA levels were observed when the crops were cultivated on brachiaria residues.