Water depths and nitrogen rates on sugarcane growth and dry biomass accumulation

Irrigation and soil fertilization management are essential agricultural practices that improve the growth and development of sugarcane plants and, consequently, increase their production capacity, which is important for sugar and alcohol productions. In this context, the objective of this work was to evaluate the effect of water depths and nitrogen rates on the growth and dry biomass accumulation of sugarcane plants. The treatments consisted in four water depths (1,498; 1,614; 1,739; and 1,854 mm), five nitrogen rates (0; 20; 40; 80; and 120 kg ha-1) and five evaluation times. The experiment was conducted in a randomized block design with a split-split-plot arrangement and four replications, including the factors water depths, nitrogen rates, and days after planting. The dry biomasses of the plant pointer, leaves and culms, culm diameter, plant height, and number of plants were analyzed. The application of nitrogen increased the sugarcane biomass, mainly the pointer (with leaves) and dry culm biomass, and the number of plants. The highest dry culm biomass accumulation and dry leaf biomass were found at the end of the crop cycle for the treatment with the application of nitrogen rates of 80 and 120 kg ha-1. The increases in water depths applied increased the number of plants per linear meter, but the culm and dry leaf biomass did not happen.

Temperature: a driving factor for Meloidogyne floridensis migration toward different hosts.

The peach root-knot nematode, Meloidogyne floridensis, is an emerging species and may become a threat to peach growers if contamination and spread are not avoided. The influence of temperature and two plants - tomato (Solanum lycopersicum) and French marigold (Tagete patula) - on the vertical migration of second-stage juveniles (J2) of M. floridensis was studied using 14-cm long segmented soil columns. Plants were transplanted into cups attached to the top of each column. Nylon meshes were placed between cups and columns to prevent downward root growth. About 1,000 freshly hatched J2 were injected into the base of the columns and then the columns were transferred to growth chambers at 20 and 26°C under a completely randomized block design with four replicates. The number of J2 in each ring of the columns as well as inside tomato or marigold roots was recorded at 3, 6, 9, and 12 days after injection (DAI). Nematode data were subjected to a repeated measures MANOVA. The presence of plants did not improve J2 migration as compared to control. M. floridensis migration was best at 20°C at first, with J2 migrating more than 13 cm as soon as 3 DAI, while it took 9 DAI for J2 to migrate long distances at 26°C. The distribution of J2 along the columns was similar at both temperatures at 12 DAI. Temperature had no influence on J2 penetration. French marigold did not hinder J2 migration, but fewer J2 penetrated its roots.

Spatial Dependence of Physical Attributes and Mechanical Properties of Ultisol in a Sugarcane Field.

This study investigates the effect of conventional tillage and application of the monoculture of sugar cane on soil health. Variables like density, moisture, texture, consistency limits, and preconsolidation stress were taken as indicators of soil quality. The measurements were made at a 120 × 120 m field cropped with sugar cane under conventional tillage. The objective of this work was to characterize the soil and to study the spatial dependence of the physical and mechanical attributes. Then, undisturbed soil samples were collected to measure bulk density, moisture content and preconsolidation stress and disturbed soil samples for classification of soil texture, and consistency limits. The soil texture indicated that soil can be characterized as sandy clay soil and a sandy clay loam soil, and the consistency limits indicated that the soil presents an inorganic low plasticity clay. The preconsolidation tests tillage in soil moisture content around 19% should be avoided or should be chosen a management of soil with lighter vehicles in this moisture content, to avoid risk of compaction. Using geostatistical techniques mapping was possible to identify areas of greatest conservation soil and greater disturbance of the ground.

Chemical attributes of soil fertilized with cassava mill wastewater and cultivated with sunflower.

The use of waste arising from agroindustrial activities, such as cassava wastewater, has been steadily implemented in order to reduce environmental pollution and nutrient utilization. The aim of this study is that the changes in chemical properties of dystrophic red-yellow latosol (oxisol) were evaluated at different sampling times after reuse of cassava wastewater as an alternative to mineral fertilizer in the cultivation of sunflower, hybrid Helio 250. The experiment was conducted at the Experimental Station of the Agricultural Research Company of Pernambuco (IPA), located in Vitória de Santo Antão. The experimental design was randomized blocks with 6 × 5 subplots; six doses of cassava wastewater (0; 8.5; 17.0; 34.0; 68.0; and 136 m(3) ha(-1)); and five sampling times (21, 42, 63, 84, and 105 days after applying the cassava wastewater), with four replications. Concentrations of available phosphorus and exchangeable potassium, calcium, magnesium and sodium, pH, and electrical conductivity of the soil saturation extract were evaluated. Results indicate that cassava wastewater is an efficient provider of nutrients to the soil and thus to the plants, making it an alternative to mineral fertilizers.