Acúmulo e liberação de P, K, Ca e Mg em crotalária e milheto solteiros e consorciados

Abstract

P, K, Ca and Mg accumulation and release by sunnhemp and millet in monocrop and intercroppingThe characteristics of legumes and grasses used as cover crops are well known, but the release rate of nutrients associated with plant biomass becomes available to crops is still little studied. The objective of this work was to quantify the nutrient accumulation and release of sunnhemp and millet in monocrop and intercropping. The experimental design was a randomized complete block with four replicates. The treatments were sunnhemp, millet, sunnhemp + millet and weeds. The accumulation of P and Mg was strongly influenced by the dry matter yield, reaching high values in the presence of sunnhemp, while the accumulation of Ca was a result of both the high content and the high dry mater yield in the treatments with the leguminous. The rate of nutrient release showed similar dynamics, with two distinct phases: the first with higher release, in first the 15 days and the second, slowest, from this phase. The intercropping did not affect the release rates of K, Ca and Mg, while the presence of sunnhemp enhanced the release of N. Sunnhemp Acúmulo e liberação de P, K, Ca e Mg em crotalária e milheto solteiros e consorciadosAs características das leguminosas e gramíneas usadas como plantas de cobertura são bastante conhecidas, mas a velocidade com que os nutrientes associados à biomassa vegetal tornam-se disponíveis às culturas é ainda pouco estudada. O objetivo deste trabalho foi determinar o acúmulo e a taxa de liberação de nutrientes de crotalária e milheto solteiros ou consorciados. O delineamento experimental adotado foi blocos ao acaso, com quatro repetições. Os tratamentos foram crotalária, milheto, crotalária + milheto e vegetação espontânea. O acúmulo de P e Mg foi influenciado pela produção de massa, com valores elevados na crotalária, enquanto o acúmulo de Ca resultou tanto do maior teor quanto da maior produção de massa nos tratamentos com a leguminosa. A liberação de nutrientes dos resíduos apresentou dinâmica semelhante, com duas fases distintas: a primeira com taxas mais elevadas nos primeiros 15 dias e a segunda mais lenta a partir dessa fase. As taxas de liberação de K, Ca e Mg foram semelhantes, independentemente dos tratamentos. Os resíduos da crotalária apresentaram maior liberação de P do que as da vegetação espontânea, com meia vida de 11 dias e a vegetação espontânea de 17 dias. O Ca foi liberado mais lentamente do que os demais nutrientes, e o Mg mais rapidamente. As plantas espontâneas e o milheto apresentam importante potencial na reciclagem de K, e a crotalária se destacou na reciclagem de Ca e Mg.Palavras-Chave: Adubação verde, reciclagem de nutrientes, Crotalaria juncea L., Pennisetum americanum L.

Adubação verde contribuindo para ciclagem de nutrientes em ambientes irrigados no semiárido brasileiro

“…Duarte Júnior & Coelho (2008) observed higher levels of P, varying from 4.8 to 6.2 g.kg ). Similar P amounts were reported by Perin et al (2010), whose accumulation of P was higher in the crotalaria (32.48 kg.ha ). Duarte Júnior & Coelho (2008) observed that C. juncea, pork beans, and black bean accumulated higher amounts of P than SV.…”

“…Menezes et al (2009), in the Goiás State, in an experimental field evaluating dry phytomass production in single crops and intercropping, observed that the intercropping millet + crotalaria and millet + pigeon pea and spontaneous vegetation produced 9.18, 6.69 and 4.86 mg.ha -1 , respectively. Perin et al (2010), in the Minas Gerais State, observed that crotalaria, millet, crotalaria + millet and spontaneous vegetation produced 9.34, 7.12, 8.04, and 4.49 mg.ha -1 of dry phytomass, respectively. Cavalcante et al (2012), in the Alagoas State, found that the phytomass production of the spontaneous vegetation (7.2 mg.ha ).…”

“…According to the researchers, this is because the SV is composed of plants adapted to region edaphoclimatic conditions. According to Perin et al (2010), the prevailing edaphoclimatic conditions at each site can also influence the phytomass production of the green manure species.…”

“…On the other hand, Perin et al (2010) ), due to the high content of this element in the phytomass of the SV. According to the same researchers, this type of vegetation can cycle amounts of K similar to the species used as green manures.…”

Levels of Crotalaria juncea on growth, production, recovery and efficiency of the use of N in broccoli

“…Green manure with legumes results in slower N mineralization compared to mineral fertilizers (Perin et al, 2010). Nitrogen mineralization of the green manure is affected by biological processes of the soil, climate and soil conditions, species, and chemical and biochemical characteristics of the material.…”