Abstract
This work had as objectives to use the Sunn Hemp (C rotalaria juncea L.) to evaluate the residual effect in the soil of levels of water salinity and nitrogen doses, and the occurrence of spatial dependence within the experimental area. In previous years, the experimental area received six consecutive trials, which tested different levels of nitrogen and water salinity on different crops. The same experimental design was applied to this trial, that is, a randomized block design with split-plots (5 x 3), corresponding to the residual effect of water salinity and nitrogen, and four replications. The variables determined were: the plant height on six dates after the sowing, and the dry mass of the shoot, root and the whole plant. The data were firstly subjected to the variance analysis of the residual effects and to the study of spatial variability through geostatistics. The variance analysis did not show significant residual effects of the levels of salinity and nitrogen doses in the soil on the height and dry mass of Sunn Hemp. It was observed a spatial dependence, from moderate to high, in all dates, for height and dry mass of Sunn Hemp.
Highlights
The green manuring is used since antiquity, and consists of the use of plant species, especially legumes, in order to recycle the soil nutrients and to fix nitrogen (AMADO et al, 2001)
The height of Crotalaria juncea, in the evaluated weeks, did not suffer significant residual effect of the factors studied (Table 2). It was not observed any significant interaction between the factors salinity and nitrogen in any of the weeks. They are corroborated by Bezerra et al (2010), who did not find residual effect of salinity, which can be assigned to the moderate resistance of the crop regarding salinity, leaching of N out of the surface layer and / or the nutrient extraction by maize, it has been fertilized with the same doses of N
Mass (MSR) and total Dry Mass (MST) of Sunn Hemp (Table 2). It was observed no residual effect in other studies, such as the findings of Nunes et al (2009), regarding the dry mass of Sunn Hemp by testing sources and levels of salinity on the seed germination; or the findings of Lima et al (2011) for the shoot dry mass of castor bean by evaluating the interaction between salinity and nitrogen levels, observing similar response to the levels of N independent on the water salinity; and the findings of Nobre et al (2010), on the variables of sunflower, by observing similar behavior of N rates at different levels of salinity in the irrigation water
Summary
The green manuring is used since antiquity, and consists of the use of plant species, especially legumes, in order to recycle the soil nutrients and to fix nitrogen (AMADO et al, 2001). Such species, known as cover crops can be used for pre-planting, consortium or post-planting of annual or perennial crops, either incorporated into the soil or not. Technology labile forms that may become available for subsequent crops, nitrogen (AMADO et al, 2002) Their profound and branched root systems extract nutrients from the deepest soil layers (ALCÂNTARA et al, 2000). Among the legumes used as green manure, Crotalaria juncea L. (Sun Hemp) is a shrubby tropical plant of annual cycle, erect and with determinate growth, widely used due to its rapid growth, large biomass production, easy decomposition, nutrient cycling and efficiency in the biological nitrogen
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
