The nitrogen fertilization, in general, minimizes the effects of salinity on plants, but the mitigating action depends on plant species, cultivar, soil texture and plant age, among other factors. The objective of this study was to evaluate the effects of irrigation water salinity and nitrogen fertilization on maize physiology and growth (Zea mays) in soils with different textures. The experiment was carried out in a greenhouse in Fortaleza City, CE, Brazil, in PVC soil columns (100 x 20 cm). The design was completely randomized using the factorial 2 x 2 x 4, referring to two soils, an Ultisol and a Quartzipsamment, nitrogen doses of 105 and 210 kg ha-1, under irrigation with saline water of 0.5, 2.0, 4.0 and 6.0 dS m-1, with four repetitions. With the exception of stem diameter, salinity of water impaired plant growth and leaf gas exchanges. The Ultisol provided better growth and physiological responses compared to the Quartzipsamment. The nitrogen doses did not mitigate growth variables except root biomass. The gas exchanges increased with the highest nitrogen dose, without interaction with the salinity.

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The objective of this work was to evaluate the variation in total and particulate organic carbon contents, carbon vertical stratification, and sensitivity index of organic matter fractions in soils with organic residues arranged in alleys in an agroforestry system, with and without use of fire, in the Caatinga biome, in Brazil. The experiment was conducted in a split-plot arrangement with four replications, with the factor fire in the plots, and the factor organic residues in the subplots. The organic residues used consisted of Gliricidia sepium plants; G. sepium plants and carnauba processing residue; G. sepium plants and bio-compost; and G. sepium plants, carnauba processing residue, and bio-compost, which were evaluated in three soil layers. The alleys with carnauba processing residue, G. sepium plants, and bio-compost presented a better maintenance of particulate, and mineral-associated organic carbon contents. Thus, the agroforestry management in alleys using these three residues was efficient for the maintenance of labile and recalcitrant organic matter compartments. Particulate organic carbon was more sensitive to changes in soil management than total organic matter content, in all alleys, presenting higher sensitivity indexes.

Irrigation and the use of cover crops are management practices that contribute to agriculture in regions with edaphoclimatic restrictions. The mentioned practices might affect the soil organic matter (SOM). In this context, the objective of this study were to evaluate the levels of total organic carbon (TOC), as well as the carbon in the chemical fractions of the SOM in an irrigated banana plantation submitted to soil conservation practice. The study was