Alana das Chagas Ferreira Aguiar

Growth and productivity of corn as affected by mulching and tillage in Alley cropping systems

Alley cropping has been considered a means of intensifying land use sustainably as an alternative to slash and burn agriculture in tropical regions. An experimental trial was used to evaluating the growth and productivity of corn under alley cropping to test the viability of this system as a sustainable land use practice in an amazonian Ultisol. The experimental layout was a completely randomized block design with four replications of six treatments: mulch with 13.4 and 8.9 t ha-1 of pigeon pea, and a control treatment without mulch of pigeon pea, with or without tillage. Sustainability of soil and crop were determined from changes on physical properties, such as total porosity, air capacity, available water capacity of the soil, net assimilation rate, crop growth rate, and leaf area index, as well as several productivity parameters, including average weight of ears, weight of 100 grains, and total dry matter. Both mulching and tillage increased the air capacity. Mulching of tilled areas protects the soil against the rainfall impact and prevented its recompaction. The reduced air capacity of the soil had a negative impact on the net assimilation rate, resulting in lower productivity in the no-mulch and no-till plots, mainly due to the reduction of grain weight.

Efficiency of an agrosystem designed for family farming in the pre-Amazon region

In the humid tropics, the continuous use of the same area reduces nutrient availability and increases the incidence of weeds. To circumvent these obstacles, farmers practice itinerant agriculture associated with slashing and burning with negative effects on the local and global environment. In search for a suitable system for humid tropical agriculture, the objective of this study was to investigate the performance of no-till alley cropping in conjunction with the use of annual legume crops grown during the off-season. The experiment was implemented in a one-hectare alley cropping system in which the leguminous tree clitoria ( Clitoria fairchildiana R.A. Howard) was used. The experimental design consisted of randomized blocks with four replications of the following treatments: Stylosanthis ( Stylosanthis capitata ), showey rattlebox ( Crotalaria spectabilis ), sunn hemp ( Crotalaria juncea ), jack bean ( Canavalia ensiformis ) and a control with clitoria alone, without an annual legume. In January 2007 and 2008, maize was planted in each alley. One hundred and twenty days after annual legumes were sown, the total biomass was recorded. Weed incidence was assessed 35 days after maize planting. Analyses of the C, N, P, K, Ca and Mg contents of the legumes were carried out. To assess soil organic matter (SOM), composite soil samples from the surface 0–5 cm were collected from experimental plots. Two adjacent areas were also sampled for comparison: a 10-year-old secondary forest and an area of conventional tillage. The SOM was fractionated using a densitometric and a granulometric method. Conventional systems reduce the silt and free light organic matter fractions more than no till. The use of annual legumes changes the composition of the weed community, replacing the more aggressive types with those less competitive. The use of showy rattlebox ( C. spectabilis ) may be an effective strategy for reducing weed density in the long-season crop. Furthermore, relative to the use of leguminous trees alone, higher yields of maize can be obtained with the use of showy rattlebox ( C. spectabilis ) and sunn hemp ( C. juncea ) without the application of additional N.

Environmental and agricultural benefits of a management system designed for sandy loam soils of the humid tropics

O manejo sustentavel dos solos de baixa fertilidade natural na agricultura familiar do tropico tem sido um grande desafio, que, se vencido, resultara em vantagens para o ambiente e para os agricultores. Este trabalho foi realizado com o objetivo de avaliar os beneficios ambiental e agronomico de um cultivo em aleias, por meio da determinacao do C sequestrado, dos indicadores da qualidade do solo e da produtividade da cultura do milho. Foram utilizadas combinacoes de quatro leguminosas, formando os tratamentos: Clitoria fairchildiana + Cajanus cajan; Acacia mangium + Cajanus cajan; Leucaena leucocephala + Cajanus cajan; Clitoria fairchildiana + Leucaena leucocephala; Leucaena leucocephala + Acacia mangium; e testemunha. O milho foi utilizado como cultura economica. Foram determinados o teor de C nos varios compartimentos da materia orgânica do solo, a CTC, o P disponivel, a saturacao por bases, a percentagem de saturacao por agua, o periodo do fator hospitalidade da raiz abaixo do nivel critico e a produtividade da cultura do milho. Conclui-se que o cultivo em aleias pode substituir o corte e a queima no tropico umido com vantagens ambientais, diminuindo a quantidade de CO2 atmosferico por meio da manutencao de um equilibrio dinâmico entre entrada e saida de C, que pode sustentar ate 10 Mg ha-1 desse elemento na liteira. Do ponto de vista agronomico, os beneficios do cultivo em aleias foram o aumento da saturacao por bases e a diminuicao da resistencia fisica a penetracao das raizes na camada de 0 a 10 cm, o que propiciou o aumento e a sustentacao da produtividade da cultura do milho.

The Importance of an Alternative for Sustainability of Agriculture around the Periphery of the Amazon Rainforest

The unsustainable use of the soil of the deforested area at the Amazonian border is one of the greatest threats to the rainforest, because it is the predominant cause of shifting cultivation in the region. The sustainable management of soils with low natural fertility is a major challenge for smallholder agriculture in the humid tropics. In the periphery of Brazilian Amazonia, agricultural practices that are recommended for the Brazilian savannah, such as saturating soils with soluble nutrients do not ensure the sustainability of agroecosystems. Improvements in the tilled topsoil cannot be maintained if deterioration of the porous soil structure is not prevented and nutrient losses in the root zone are not curtailed. The information gleaned from experiments affirms that in the management of humid tropical agrosystems, the processes resulting from the interaction between climatic factors and indicators of soil quality must be taken into consideration. It must be remembered that these interactions manifest themselves in ways that cannot be predicted from the paradigm established in the other region like the southeast of Brazil, which is based only on improving the chemical indicators of soil quality. The physical indicators play important role in the sustainable management of the agrosystems of the region and for these reasons must be considered. Therefore, alley cropping is a potential substitute for slash and burn agriculture in the humid tropics with both environmental and agronomic advantages, due to its ability to produce a large amount of residues on the soil surface and its effect on the increase of economic crop productivity in the long term. The article presents some promising patents on the importance of an alternative for sustainability of agriculture.

Comportamento de dois genótipos de milho cultivados em sistema de aléias preestabelecido com diferentes leguminosas arbóreas

O cultivo em aleias tem sido recomendado como alternativa para a substituicao da agricultura de corte e queima, no tropico umido, devido a grande capacidade de producao de materia orgânica e de reciclagem de nutrientes, mas algumas duvidas quanto a sustentabilidade e a competicao interespecifica sao persistentes. O objetivo no trabalho foi avaliar a viabilidade da cultura do milho em um sistema de cultivo em aleias de leguminosas arboreas. O delineamento experimental utilizado foi em blocos casualisados, com quatro repeticoes dos tratamentos: aleias de sombreiro (Clitoria fairchildiana), inga (Inga edulis), guandu (Cajanus cajan) e leucena (Leucaena leucocephala) e uma testemunha sem aleias. Foram avaliadas a remobilizacao de carbono e nitrogenio, massa de graos, massa de mil graos e competicao interespecifica entre as cultivares de milho e as leguminosas. A producao de graos foi maior nas parcelas com C. fairchildiana e L. leucocephala. A produtividade do hibrido de milho foi superior a da variedade em todos os tratamentos. A produtividade e a massa de mil graos de milho nao sao negativamente afetadas pela distância da linha da leguminosa arborea. Esse estudo conclui que o sistema de aleias com leguminosas arboreas e uma alternativa importante ao manejo sustentavel dos agroecossistemas no tropico umido. Alem disso, nessa regiao a produtividade em graos na cultura do milho e favorecida no sistema de aleias preeestabelecidas com as leguminosas arboreas sombreiro, inga e leucena e pela utilizacao de genotipos eficientes no aproveitamento do nitrogenio, cujo sincronismo entre a liberacao e a absorcao do N aplicado por meio das leguminosas deve ser aprimorado.

Effectiveness of calcined rock phosphate and leucaena prunings as a source of nutrients for maize in a tropical soil

Cost reduction and an increased efficiency in the utilization of nutrients are essential for establishing agricultural systems in the tropics. The combined effects of calcined Al phosphate (ALP) and leucaena prunings (L) on the agronomic efficiency and on the efficiency of physiological use of nitrogen (N) and phosphorus (P) in maize were assessed. The treatments consisted of 160 kg ha− 1 of P2O5 from ALP and 100 kg ha− 1 of N from urea (ALP+U); 160 kg ha− 1 of P2O5 from ALP and 6 Mg ha− 1 of L (ALP+L); 160 kg ha− 1 of P2O5 from single superphosphate (SSP) and 100 kg ha− 1 of N from U (SSP+U); 160 kg ha− 1 of P2O5 from SSP and 6 Mg ha− 1of L (SSP+L); and a control without fertilization. The decreasing order of effectiveness among treatments was SSP+L > ALP+L > SSP+U > ALP+U > control. Both leucaena–phosphate combinations had beneficial effects on the growth of the maize, the N and P recovery, and the agronomic efficiencies. Both ear weight and grain weight were higher under the SSP+L treatment than under the SSP+U treatment and higher under the ALP+L treatment than under the ALP+U treatment. The low N and P agronomic efficiency in maize grown under the ALP+U treatment made the combined use of these fertilizers undesirable. The satisfactory efficiency of grain production shown by the maize grown under ALP+L indicated that this treatment could replace processed fertilizers for use in agrosystems management in the tropics.

Soil Management and Efficiency of Rhizobia Strains of Cowpea Vigna unguiculata (L.) Walp. in the Tropics

En los tropicos humedos, el mayor obstaculo para la aplicacion de sistemas de agricultura sostenible es la reduccion de la eficiencia del uso de nutrientes por los cultivos. Este estudio evalua la eficacia de cinco cepas de rizobios seleccionados en simbiosis con frijol (Vigna unguiculata (L.) Walp.), con el objetivo de sustituir la fertilizacion nitrogenada en el sistema de uso de suelo predominante utilizado por los pequenos agricultores. El estudio se llevo a cabo en tres zonas adyacentes de distintos usos agricolas: labranza convencional, agricultura itinerante, y un sistema de no laboreo. El diseno experimental fue en bloques al azar con cuatro repeticiones y siete tratamientos: cinco cepas de rizobios (BR3262, BR3267, BR3299, INPA3-11B y UFLA 3-84) y dos controles sin inocular (uno sin N mineral y otro fertilizado con 74 kg de N ha-1). Se midio el peso en seco de 100 granos, de los nodulos y de los brotes, asi como los rendimientos de frijol y se calcularon los indices de eficiencia relativa y absoluta para la produccion de biomasa seca de los brotes de frijol. El sistema de uso del suelo afecta el numero y peso en seco de los nodulos y, en consecuencia, la masa de la materia vegetal seca y el rendimiento del frijol. En terminos de rendimiento, hubo una gran diferencia entre el convencional y los sistemas itinerantes. La productividad fue alrededor de cuatro veces mayor en la agricultura itinerante (1009,9 kg ha-1 en comparacion con 243,7 kg ha-1). En condiciones de suelos propensos a la cohesion, el sistema de labranza convencional reduce la posibilidad de cultivo de una segunda cosecha en el ano, incluso con la inoculacion o la fertilizacion nitrogenada.

Avaliação de um sistema de cultivo em aléias em um argissolo franco-arenoso da região amazônica.

No tropico umido, a construcao e manutencao da fertilidade dos solos sao os maiores desafios dos que se dedicam a implantacao de sistemas agricolas sustentaveis. O objetivo deste estudo foi avaliar um sistema de cultivo em aleias com guandu, associado a adicao anual de calcario e de K, em um Argissolo de textura franco-arenosa, a fim de verificar a possibilidade do uso desse sistema como alternativa ao corte e queima na agricultura do tropico umido. Foram utilizados, como leguminosa, o guandu (Cajanus cajan) e a cultura do milho. Os tratamentos foram os seguintes: T = testemunha, com solo desnudo; G2, G2,5 e G3, tratamentos com fileiras de guandu nos espacamentos de 2, 2,5 e 3 m, respectivamente; G2K, G2,5K e G3K, tratamentos com guandu nos mesmos espacamentos mais K; G2C, G2,5C e G3C, tratamentos com guandu mais calagem; G2KC, G2,5KC e G3KC, tratamentos com guandu mais K e calagem. A cobertura e o equilibrio de nutrientes do solo foram os mais importantes fatores que influenciaram a produtividade do milho no sistema de cultivo em aleias com guandu; portanto, eles devem ser considerados como fundamentais para o manejo sustentavel dos Argissolos de textura franco-argilosa do tropico umido.

Crescimento e produtividade de duas cultivares de milho de alta qualidade protéica em solo de baixa fertilidade

Maize cultivars with protein of high biological value (QPM) developed by EMBRAPA would be a good alternative for the Brazilian low income farmers, but in the humid tropic their performances should be confirmed under local prevalent field conditions. A field experiment was done in January, 1999, in an Argisol and under the system of alley cropping, with plots of 4 x 6 m2 and four replications, to evaluate the growth and productivity of two high quality protein maize cultivars (BR 473 and BR 2121) in comparison to three other related cultivars used in the farming system of Maranhao state: Ferro (traditional cultivar, collected with local farmers), BR 106 and AG 1051 (low and medium technological level respectively). The leaf rate index, net assimilation rate, the number of cob, grain yield per cob, cob and 100 grains weight, and harvest index were evaluated. The results showed that cultivar BR 473 can be recommended to be cultivated in chemically stressed soil and high temperature conditions. The cultivar AG 1051 presented higher grain yield. The general use of local traditional cultivar Ferro by low income farmers can only be justified by the possibility of field storage, since its productivity was less than all other cultivars tested.

Chemical and physical fertility indicators of a weakly-structured Ultisol after liming and mulching.

No tropico umido, os indicadores quimicos e fisicos, que diminuem a disponibilidade de nutrientes e aumentam a deficiencia de oxigenio dos solos, sao importantes para diagnosticar restricoes ao crescimento das culturas. Avaliaram-se as relacoes entre o crescimento das plantas e os principais indicadores fisicos e quimicos da fertilidade de um Argissolo desenvolvido em sedimentos da Formacao Itapecuru, no Centro-Norte do Maranhao. O experimento foi instalado em blocos casualizados, com quatro repeticoes e seis tratamentos: 6,0 Mg ha-1 de cobertura morta com e sem calagem; 3,0 Mg ha-1 de cobertura morta com e sem calagem; solo descoberto com e sem calagem. Nas plantas, foram determinados o indice de area foliar, a taxa de assimilacao liquida e os parâmetros de produtividade: numero e peso medio das espigas, peso de 100 graos, indice de colheita e producao total de graos. No solo foram avaliadas as variacoes nas densidades na sua superficie e a 20 cm, a evolucao da porosidade efetiva apos alagamento provocado e as alteracoes em indicadores quimicos como capacidade de troca cationica, saturacao por bases, carbono orgânico e teores de macronutrientes. A cobertura morta e a calagem se equivaleram quanto a influencia na producao da area foliar, mas a cobertura morta foi mais importante para a produtividade do milho, devido ao seu maior efeito sobre a fotossintese liquida das plantas.