Abstract
Choosing species with high phytomass production to be cropped in no tillage system is extremely important in dry winter regions. The purpose of this research was to study plant biomass production and accumulation of nutrients in shoots of sorghum plants (Sorghum bicolor subspecies bicolor race Guinea) sown in different sowing dates. A randomized complete block design with six treatments and four replications was performed. Treatments consisted of six sowing dates (09/25/2000; 10/25/2000; 11/24/2000; 12/22/2000; 02/22/2001 and 04/03/2001). At flowering, dry matter production, number and diameter of stems and plant height were evaluated. Macro and micronutrient levels and accumulation were determined as well as C/N ratio. Plant cycle decreased as sowing date was delayed and, consequently, dry matter production and C/N ratio decreased as well. The opposite was observed for nutrient contents. Giant Guinea sorghum is sensitive to photoperiod thus late sowing reduces plant development, which leads to low biomass production and nutrient accumulation. Giant Guinea sorghum cultivated as cover crop is a good option when implementing no tillage system due to high dry matter production and N, P, and K recycling.
Highlights
Cover crop species are usually aggressive and rugged because of their deep and branched root system, which are efficient to extract nutrients from deeper soil layers
Cover crop residues that remain on soil surface may enhance water infiltration, decrease water losses through evaporation, maintain soil humidity and temperature stability, improve weed control and increase nutrient cycling effectiveness (ROSOLEM et al, 2007)
Positive effects of maintaining crop residues on soil surface are observed in time, depending on the species, decomposition rate, quantity, contact with soil, chemical composition and, especially, C/N ratio (ROSOLEM et al, 2004)
Summary
Cover crop species are usually aggressive and rugged because of their deep and branched root system, which are efficient to extract nutrients from deeper soil layers. Afterwards, plant decomposition releases nutrients to soil superficial layers, subsequently becoming available to succeeding crops (AMABILE et al, 2000; CRUSCIOL et al, 2005; GARCIA et al, 2008; PAVINATO; ROSOLEM, 2008). Cover crop residues that remain on soil surface may enhance water infiltration, decrease water losses through evaporation, maintain soil humidity and temperature stability, improve weed control and increase nutrient cycling effectiveness (ROSOLEM et al, 2007). Positive effects of maintaining crop residues on soil surface are observed in time, depending on the species, decomposition rate, quantity, contact with soil, chemical composition and, especially, C/N ratio (ROSOLEM et al, 2004)
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