Abstract
Organomineral fertilizers have been used to meet plants’ nutritional needs and reduce producers’ reliance on mineral fertilizers. This study aimed to determine the effect of organic matter sources for organomineral fertilizers and traditional mineral fertilizers to the sorghum initial development. The experiment followed a randomized complete block design in a ‘4 x 3 + 2’ factorial arrangement, with four fertilizer doses (50, 75, 100 and 125%) of the recommended dose for sorghum crops (450 kg ha-1), three organic matter sources to compose the organomineral fertilizers (sewage sludge, filter cake, peat), a control (mineral fertilizer), and an untreated check (no fertilizers). Each experimental plot consisted of four plants divided into two pots. Plant height, stem diameter, chlorophyll a, chlorophyll b, and leaf area were performed at 30 and 60 days after seeding (DAS) when shoot dry mass was also measured. Organomineral fertilizers outperformed both control and untreated check plots for most variables at 30 DAS. Sorghum fertilized with organomineral fertilizers also showed positive results at 60 DAS, even with dose reductions. Considering the variables herein reported, organomineral fertilizers can replace mineral fertilizers in the development of sorghum, even with dose reductions. Key words: Biofertilizer, sewage sludge, filter cake, peat, plant nutrition.
Highlights
High grain yields require high agronomic inputs, and among these, mineral fertilizers represent major investments, with approximately 13 and 24% of the total investment on sorghum (Sorghum bicolor (L.) Moench) crop production cycle (Wylie, 2008; USDA, 2016)
Due to the need to find alternative sources to reduce production costs related to mineral fertilization, the lack of information on organomineral fertilizer application in sorghum and the possibility of correctly allocate an environmental waste produced by different sectors, this study aimed to evaluate the ability of organomineral fertilizers made from different sources of organic compounds to replace the application of mineral fertilizers on sorghum crop
The experimental design consisted of randomized blocks with four replications in a factorial structure ‘4 x 3 + 2’, corresponding to four levels of organomineral fertilizer (50, 75, 100 and 125% of the dose of 450 kg ha-1 of NPK 5-17-10, according to the recommendation of Ribeiro et al, 1999), three sources of organic matter for the organomineral fertilizer, and two additional treatments, being a treatment with mineral fertilization corresponding to 100% of the dose of organomineral fertilizer, and a control treatment with no fertilization
Summary
High grain yields require high agronomic inputs, and among these, mineral fertilizers represent major investments, with approximately 13 and 24% of the total investment on sorghum (Sorghum bicolor (L.) Moench) crop production cycle (Wylie, 2008; USDA, 2016). Despite the large costs, appropriate management of fertilizers and of the soil fertility increases considerably the productivity of crops (Lopes and Guilherme, 2007; Hawkesford et al, 2014). The fertilization with organic compounds is an option to the exclusive use of mineral fertilizers in agricultural production systems. Organic fertilizers are any product derived from plants, animals, urban or industrial residues, which is composed of degradable carbon, and may be any substance that is present in the soil and has as source plants, microorganisms, excretions of fauna and everything that turns into humus after the decomposition (Silva and Mendonça, 2007; Chem, 2015).
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