Daniel da Costa Dantas

Produção e qualidade do meloeiro cultivado com filmes plásticos em respostas à lâmina de irrigação

A demanda por tecnicas que aumentem a produtividade do melao e proporcionem a padronizacao dos frutos nas caracteristicas desejaveis pelos consumidores como, elevado teor de solidos soluveis e firmeza de polpa, bom sabor e boa aparencia externa, e uma realidade. A cobertura do solo com filmes plasticos e uma tecnica que foi introduzida no agro-polo Assu-Mossoro-Barauna para suprir essa demanda. Por outro lado, o uso de cobertura do solo com filmes plasticos modifica a evapotranspiracao das areas cultivadas, necessitando de ajustes da lâmina de irrigacao. Objetivou-se com este trabalho avaliar o efeito de quatro lâminas de irrigacao (L1 -100%; L2 - 91%; L3 - 82% e L4 - 72% da lâmina padrao de 452 mm, a qual foi determinada pela metodologia do Kc dual da FAO) e tres tipos de filmes de polietileno (branco-preto, prata-preto e preto-preto) na cobertura do solo, comparando com o cultivo sem cobertura, na producao e qualidade dos frutos do meloeiro. A utilizacao dos filmes de polietileno proporcionou um aumento expressivo na produtividade, sendo o aumento no peso dos frutos de 20% em media em relacao ao tratamento com solo descoberto; os filmes de polietileno de coloracao branco-preto e preto-preto sobressairam em relacao ao de cor prata-preto; a lâmina padrao de 452 mm pode ser reduzida em ate 28% sem alterar a producao mesmo havendo reducao do peso medio dos frutos em 11%; a concentracao de solidos soluveis diminuiu a medida que a lâmina de irrigacao foi reduzida, devido ao intenso ataque de pragas.

Evolução da salinidade e pH de solo sob cultivo de melão irrigado com água salina

ABSTRACT This work aimed to study the effects of irrigation with saline waters in an area cultivated with melon onsoil salinity and pH. The experiment was conducted in the Santa Julia Farm, Mossoro city, Rio Grande doNorte State, Brazil, during the years 2001 to 2002. Water with different salinity levels (0.6; 1.9; 3.2 and4.5 dS m -1 ) was used throughout the cycle and in incremental way in three periods of melon development,forming 15 treatments, arranged in randomized blocks with four replications. The salinity was measuredat 0, 30, 50 and 70 days after sowing in soil samples collected in layers of 0-15, 15-30 and 30-45 cm.There was greater accumulation of salts in the surface layer (up to 15 cm) in all salinity levels and the useof more saline water produced higher average salinity in the profile. The average values of pH werewithin the range of optimal absorption of nutrients required by melon. Key words : Cucumis melo L., electrical conductivity, water management Revista Brasileira deEngenharia Agricola e Ambiental

ANÁLISE DE CRESCIMENTO E PRODUTIVIDADE DO GIRASSOL ADUBADO COM ÁGUA RESIDUÁRIA DA MANDIOCA

Cassava wastewater is the liquid residue of the cassava flour processing and its application to the soil as fertilizer for agricultural crops is a good alternative to sources of nutrients for plants. In this context, the objective of this work was to evaluate the growth and seed yield of sunflower on soil fertilized with cassava wastewater. A randomized block experimental design with four replications was used, with six cassava wastewater rates (0, 8.5, 17, 34, 68 and 136 m ha) and six plant sampling times (15, 30, 45, 60, 75 and 90 days after sowing), using the sunflower cultivar Helio-250. The evaluated variables were total leaf area, leaf area index, leaf area ratio, specific leaf area, leaf weight ratio, shoot dry mass and sunflower seed yield. The use of cassava wastewater rate of 136 m ha increases the seed yield, leaf area, leaf area index and shoot dry mass, and results in lower leaf area ratio, specific leaf area and leaf weight ratio of sunflower (cv. Helio-250) crops.

Chemical attributes of soil fertilized with cassava mill wastewater and cultivated with sunflower.

The use of waste arising from agroindustrial activities, such as cassava wastewater, has been steadily implemented in order to reduce environmental pollution and nutrient utilization. The aim of this study is that the changes in chemical properties of dystrophic red-yellow latosol (oxisol) were evaluated at different sampling times after reuse of cassava wastewater as an alternative to mineral fertilizer in the cultivation of sunflower, hybrid Helio 250. The experiment was conducted at the Experimental Station of the Agricultural Research Company of Pernambuco (IPA), located in Vitória de Santo Antão. The experimental design was randomized blocks with 6 × 5 subplots; six doses of cassava wastewater (0; 8.5; 17.0; 34.0; 68.0; and 136 m3 ha−1); and five sampling times (21, 42, 63, 84, and 105 days after applying the cassava wastewater), with four replications. Concentrations of available phosphorus and exchangeable potassium, calcium, magnesium and sodium, pH, and electrical conductivity of the soil saturation extract were evaluated. Results indicate that cassava wastewater is an efficient provider of nutrients to the soil and thus to the plants, making it an alternative to mineral fertilizers.