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Authors
Abstract(s)
As leguminosas anuais cultivadas como adubo verde podem variar em seu valor
fertilizante dependendo de vários fatores, como a espécie de leguminosa, o manejo
agronómico e as condições do solo. No entanto, em geral, as leguminosas anuais têm um
alto valor fertilizante devido à sua capacidade de fixar azoto atmosférico através da
simbiose com bactérias da família Rizobiaceae. O azoto é um nutriente essencial para o
crescimento das plantas, mas muitas vezes é limitado no solo. As leguminosas anuais têm
a capacidade de fixar azoto atmosférico e convertê-lo em uma forma utilizável pelas
plantas. Essa fixação de azoto ocorre dentro dos nódulos das raízes das leguminosas, onde
as bactérias fixadoras transformam azoto elementar em amónia e outros compostos
nitrogenados. Além de fornecer azoto para as plantas, as leguminosas anuais também
podem melhorar a saúde do solo e aumentar sua fertilidade. Isso ocorre porque as raízes
das leguminosas podem penetrar profundamente no solo, contribuindo para diminuir os
riscos de compactação e usando nutrientes que estavam nas camadas mais profundas.
Além disso, as leguminosas anuais também podem melhorar a estrutura do solo, aumentar
a matéria orgânica e a capacidade de retenção de água. Neste trabalho, avaliou-se o valor
fertilizante de leguminosas e gramíneas, incluindo seu potencial de incorporação de azoto
no solo e o favorecimento na absorção de outros nutrientes, em duas áreas de olival de
sequeiro com solos ácidos. O primeiro ensaio foi instalado na quinta do Valongo em
Mirandela, no Nordeste de Portugal. O segundo ensaio foi instalado em Bragança na
quinta do Pinheiro Manso. Cada ensaio consistiu em 11 talhões, sendo cada um
delimitado por quatro oliveiras num compasso 7 m × 7 m, a que correspondem 49 m2,
onde se semearam individualmente, fava (Vicia faba, cvs. Favel e Vesúvio), tremoço-
branco (Lupinus albus, cv. Estoril), treomoço-de-folha-estreita ou tremoço-azul (Lupinus
angustifolium, cv. Karo), tremocilhas (Lupinus luteus, cvs. Nacional e Mister), trevo-
encarnado (Trifolium incarnatum, cv. Diogene), trevo-subterrâneo (Trifolium
subterraneum, cvs. Campeda e Dalkeith), aveia (Avena sativa, cv. Boa Fé) e azevém
anual (Lolium multiflorum, cv. Falladino). As plantas foram colhidas ao longo de três
fases distintas (março a maio) e levadas para estufa de secagem regulada a 70 oC até
atingirem peso constante, sendo posteriormente pesadas, moídas e analisadas para a
composição elementar dos seus tecidos. Nos dois ensaios, as tremocilhas, cvs. Nacional
(7,27 t ha-1 e 8,28 t ha-1) e o tremoceiro-azul, cv. Karo (7,21 t ha-1 e 8,83 t ha-1),
apresentaram os maiores valores de matéria seca, assim como maior acumulação de azoto,
revelando-se as mais promissoras para adubação verde, constituindo-se como uma
importante fonte de azoto para a cultura principal e para a melhoria da fertilidade do solo.
Annual legumes grown as green manure can vary in their fertilizing value depending on several factors, such as the legume species, agronomic management and soil conditions. However, in general, annual legumes have a high fertilizing value due to their ability to fix atmospheric nitrogen through symbiosis with bacteria of the Rizobiaceae family. Nitrogen is an essential nutrient for plant growth, but it is often limited in the soil. Annual legumes have the ability to fix atmospheric nitrogen and convert it into a form usable by plants. This nitrogen fixation occurs in the root nodules of legumes, where bacteria transform elemental nitrogen into ammonia and other nitrogenous compounds. In addition to providing nitrogen to plants, annual legumes can also improve soil health and increase soil fertility. This is because legume roots can penetrate deep into the soil, helping to reduce the risks of compaction and releasing nutrients that were taken up from deeper layers. Additionally, annual legumes can also improve soil structure and increase organic matter and water holding capacity. In this work, the fertilizing value of legumes and grasses was studied evaluating their potential for incorporating nitrogen into the soil and favoring the uptake of other nutrients, in two plots of rainfed olive groves with acidic soils. One experiment was installed at Quinta do Valongo in Mirandela, in the Northeast of Portugal. The second trial was installed in Bragança on the Pinheiro Manso farm. Each trial consisted of 11 plots, each delimited by four olive trees in a 7 m × 7 m space, corresponding to 49 m2, where were sown individually, broad beans (Vicia faba, cvs. Favel and Vesúvio) and white lupine (Lupinus albus, cv. Estoril), narrow-leaf lupine or blue lupine (Lupinus angustifolium, cv. Karo), lupins (Lupinus luteus, cvs. Nacional and Mister), red clover (Trifolium incarnatum, cv. Diogene), subterranean clover (Trifolium subterraneum, cvs. Campeda and Dalkeith), oats (Avena sativa, cv. Boa Fé) and annual ryegrass (Lolium multiflorum, cv. Falladino). The plants were sampled three times (from March to May), oven-dried at 70 oC until they reached a constant weight, and subsequently weighed, ground and analyzed for the elemental composition in their tissues. In both experiments, lupins, cvs. Nacional (7.27 t ha-1 and 8.28 t ha-1) and blue lupine, cv. Karo (7.21 t ha-1 and 8.83 t ha-1), presented the highest dry matter values, as well as the highest nitrogen accumulation, proving to be the most promising for green manure, constituting an important source of nitrogen for the main crop and for improving soil fertility.
Annual legumes grown as green manure can vary in their fertilizing value depending on several factors, such as the legume species, agronomic management and soil conditions. However, in general, annual legumes have a high fertilizing value due to their ability to fix atmospheric nitrogen through symbiosis with bacteria of the Rizobiaceae family. Nitrogen is an essential nutrient for plant growth, but it is often limited in the soil. Annual legumes have the ability to fix atmospheric nitrogen and convert it into a form usable by plants. This nitrogen fixation occurs in the root nodules of legumes, where bacteria transform elemental nitrogen into ammonia and other nitrogenous compounds. In addition to providing nitrogen to plants, annual legumes can also improve soil health and increase soil fertility. This is because legume roots can penetrate deep into the soil, helping to reduce the risks of compaction and releasing nutrients that were taken up from deeper layers. Additionally, annual legumes can also improve soil structure and increase organic matter and water holding capacity. In this work, the fertilizing value of legumes and grasses was studied evaluating their potential for incorporating nitrogen into the soil and favoring the uptake of other nutrients, in two plots of rainfed olive groves with acidic soils. One experiment was installed at Quinta do Valongo in Mirandela, in the Northeast of Portugal. The second trial was installed in Bragança on the Pinheiro Manso farm. Each trial consisted of 11 plots, each delimited by four olive trees in a 7 m × 7 m space, corresponding to 49 m2, where were sown individually, broad beans (Vicia faba, cvs. Favel and Vesúvio) and white lupine (Lupinus albus, cv. Estoril), narrow-leaf lupine or blue lupine (Lupinus angustifolium, cv. Karo), lupins (Lupinus luteus, cvs. Nacional and Mister), red clover (Trifolium incarnatum, cv. Diogene), subterranean clover (Trifolium subterraneum, cvs. Campeda and Dalkeith), oats (Avena sativa, cv. Boa Fé) and annual ryegrass (Lolium multiflorum, cv. Falladino). The plants were sampled three times (from March to May), oven-dried at 70 oC until they reached a constant weight, and subsequently weighed, ground and analyzed for the elemental composition in their tissues. In both experiments, lupins, cvs. Nacional (7.27 t ha-1 and 8.28 t ha-1) and blue lupine, cv. Karo (7.21 t ha-1 and 8.83 t ha-1), presented the highest dry matter values, as well as the highest nitrogen accumulation, proving to be the most promising for green manure, constituting an important source of nitrogen for the main crop and for improving soil fertility.
Description
Mestrado de dupla diplomação com o Instituto Superior Politécnico de Gaza
Keywords
Fixação biológica do azoto Leguminosas anuais Adubos verdes