Alberto Carlos de Campos Bernardi

Urea–Montmorillonite-Extruded Nanocomposites: A Novel Slow-Release Material

The present study describes the preparation and characterization of a novel urea slow-release nanocomposite, based on urea intercalation into montmorillonite clay by an extrusion process at room temperature. Nanocomposites with urea contents ranging from 50 to 80 wt % were successfully produced and characterized. Analyses by XRD, DTA, and SEM-EDX confirmed the effectiveness of this simple process to exfoliate the clay lamellae into the urea matrix, forming a product that can be classified as a nanocomposite, due to the exfoliation degree attained. Diametral compression tests showed that the samples were very deformable, and the release rate of active components in water showed that the nanocomposite showed a slow release behavior for urea dissolution, even in low montmorillonite amounts (20% in weight).

Brazilian sedimentary zeolite use in agriculture

This report describes the characterization and application of the Brazilian zeolitic sedimentary rocks as a slow plant-nutrient fertilizer and soil conditioner. The characterization of the head samples showed that it is composed of the zeolite stilbite intertwined with a smectic clay mineral, mixed with quartz. A lowcost quartz separation gravitational technique was used to concentrate the mineral. An enrichment of concentrated natural zeolite was carried out by adding KNO3 ,K 2HPO4 and H3PO4 + apatite. These materials were tested with Rangpur lime rootstock and other with four successive crops grown on the same substrate: lettuce, tomato, rice, and Andropogon grass. The results indicated that N, P and K enriched zeolite was an adequate slow-release source of nutrients to plants increasing 20% of crop production and also improving products quality. Other green house and field experiments with concentrated zeolite applied with urea showed 8% of reduction on losses of ammonia volatilization and improving 5% the corn dry matter yield. Concentrated zeolite used as a sand soil amendment also increased at least 10% of soil water retention and 15% of available water capacity.

Estimativa da acidez potencial pelo pH SMP em solos do semi-árido do Nordeste brasileiro

In this study the relationship between the pH SMP and H + Al concentrations was evaluated, in order to establish an equation for estimating the potential acidity of soils from Northeastern Brazil. The H + Al concentration (calcium acetate 0.5 mol L-1, pH 7.0) and pH SMP were analyzed in 81 soil samples. Soil carbon content ranged from 1.8 to 35.6 g kg-1, and clay content varied from 60 to 590 g kg-1. The equation H + Al = 31.521(pH SMP)2 -451.61 pH SMP + 1625.3 (R2 = 0.87**), with H + Al in mmolc dm-3, provides a good estimation of potential acidity by using the pH SMP.

Dry matter production and nutrient accumulation after successive crops of lettuce, tomato, rice, and andropogongrass in a substrate with zeolite

SUMMARY Zeolites are hydrated crystalline aluminosilicate minerals of natural occurrence, structured in rigid third dimension net that can be used as slow release plant-nutrient source. The main objective of this study was to evaluate the effects of plant growth substrate under zeolite application, enriched with N, P and K, on dry matter yield and on nutrient contents in consecutive crops of lettuce, tomato, rice, and andropogon grass. The experiment was carried out in a greenhouse, with 3 kg pots with an inert substrate, evaluated in a randomized block design with three replications. Treatments consisted of four types of enrichment of concentrated natural zeolite: concentrated zeolite (Z) only, zeolite + KNO3 (ZNK), zeolite + K2HPO4 (ZPK) and zeolite + H3PO4 + apatite (ZP), and a control grown in substrate fertilized with a zeolite-free nutrient solution. Four levels of enriched zeolite were tested: 20, 40, 80, and 160 g/pot. Four successive crops were grown on the same substrate in each pot: lettuce, tomato, rice, and andropogon grass. Results indicated that N, P and K enriched zeolite was an adequate slow-release nutrient source for plants. The total dry matter production of above-ground biomass of four successive crops followed a descending order: ZP > ZPK > ZNK > Z.

Nutrient release by a Brazilian sedimentary zeolite

This report describes the characterization of a sedimentary occurrence from the Parnaiba Basin, Brazil, containing the zeolite stilbite intertwined with smectitic clay mineral. The head samples from different sites present a wide content range of the zeolitic phase – 15% to 50%. The use of simple separation techniques – conventional gravitic treatments – yields concentrates containing about 67% of the zeolitic component. Assays with the amendments of these concentrates with plant nutrients yield release rates matching those reported for similar commercial products.

ANALYTICAL QUALITY PROGRAM OF SOIL FERTILITY LABORATORIES THAT ADOPT EMBRAPA METHODS IN BRAZIL

The analytical quality program of soil fertility laboratories that adopt the Embrapa methods (PAQLF) is a voluntary national sample-exchange program. PAQLF is managed by Embrapa Solos (National Soil Research Center), and actually is comprised of 82 Brazilian soil fertility laboratories that use P and K extraction with Mehlich-1 solution; Al, Ca, and Mg with KCl solution; soil pH in water; and total organic C by colorimetric or Walkley–Black methods. The quality of soil-test results is evaluated by true values taken as mean (accuracy) following removal of outliners by up to three interactions until CV falls below 20%, and by sample with three replications (precision). Inaccuracy and Imprecision Index are calculated for all laboratories and a ranking is established by an Excellence Index. Yearly the best ranked laboratories are indicated and qualified to use the Quality Control Seal. The objective of this research was to evaluate the performance in regard to accuracy and precision, characterize soil-testing laboratories and show the performance evolution of this program. The program involves a quarterly exchange of 8 soil samples on which soil fertility analyses are required and micronutrient (B, Cu, Fe, Mn, and Zn) optionally conducted. Laboratories characteristics included kinds of analysis, facilities, methods, quality assurance, and management. In 2000, 79 laboratories from 23 Brazilian states took part in the program, representing 350,000-soil fertility samples. Results indicate an improvement in the laboratories quality analysis through the course of this 9-years program. Laboratories characteristics indicated what efforts should be addressed to improve the quality in the future.

Yield, Quality Components, and Nitrogen Levels of Silage Corn Fertilized with Urea and Zeolite

The zeolite and urea mixture may be use to improve nitrogen (N)–use efficiency of silage corn. The objective of this study was to evaluate dry-matter yield and nutritional levels of N of silage corn fertilized with urea and zeolite mixture. The experimental design was a 2 × 4 × 4 factorial randomized block design with three replications. Treatments included two types of stilbite zeolite (natural and concentrated), four levels of nitrogen (0, 50, 100, and 200 kg ha−1), and four ratios of zeolite (25%, 50%, and 100% of N level). Treatments were applied 60 days after planting with the topdressing fertilization. The use of concentrated (650 g kg−1 of stilbite) or natural (470 g kg−1 of stilbite) zeolite with urea increased silage corn dry-matter production and leaf N concentrations.

Crescimento e nutrição mineral do porta-enxerto limoeiro 'Cravo' cultivado em substrato com zeólita enriquecida com NPK

The main objective of this research was to evaluated the growth, dry matter production, leaf area, N, P and K levels and exportation and chlorophyll levels of Rangpur Lime (Citrus limonia Osbeck) grown in a substrate with NPK enriched zeolite. Rootstocks were cultivated during 93 days in 150cm3-dibble tubes containing composted organic substrate of cocopeat and vegetal coal (3:1) with zeolite addition. Treatments comprised 4 levels (0, 2.5, 5, 10 and 15 g per plant) of a NPK-enriched zeolite, which was a mix of H3PO4/apatite-zeolite (70%) and KNO3 - zeolite (30%). Results indicated that the supply of nutrients through the mineral zeolite enriched with NPK added to the organic substrate was a viable alternative for citrus rootstock production in protecting environment. The supply of 6,4 g of enriched zeolite significantly increased dry matter production, leaf area, height and steam diameter. These increases were 37,5% in relation to the control without zeolite. N, P and K foliar levels increased with zeolite enriched with NPK. Chlorophyll levels were related to N levels, pointed out to be a useful tool for Rangpur Lime nutritional status evaluation.

Carbon and nitrogen stocks of an Arenosol under irrigated fruit orchards in semiarid Brazil

O acumulo de materia orgânica beneficia a produtividade do solo e reduz a concentracao do carbono atmosferico. Entretanto, pouco e sabido a respeito do acumulo de C e N em solos arenosos cultivados com culturas perenes irrigadas em regioes semi-aridas. O objetivo deste trabalho foi avaliar o efeito do cultivo de fruteiras irrigadas nos estoques de C e N de um Neossolo Quartzarenico em Paraipaba, CE. Foram coletadas amostras na linha e na entrelinha de pomares irrigados de banana, caju, manga, sapoti, goiaba e graviola. Em areas adjacentes sob vegetacao de Caatinga hipoxerofila e apos dois anos de desmatamento foram coletadas amostras adicionais. As profundidades de amostragem foram: 0 a 0.1, 0.1 a 0.2 e 0.2 a 0.4 m. Os teores de C e N no solo foram mais altos na camada superficial (0 a 0.1 m). Nao houve efeito da profundidade de amostragem sobre a densidade do solo. Os estoques de C e N na area com vegetacao de Caatinga na camada de 0 a 0.4 m foram de 27,6 and 2,4 Mg ha-1, respectivamente. A retirada da vegetacao natural e o cultivo das fruteiras levaram a reducoes de 5 a 23% e 4 a 21% nos estoques de C e N do solo, respectivamente. As culturas do sapoti e da graviola contribuiram para o aumento dos estoques de C e N apos a retirada da vegetacao natural. As culturas da goiaba, graviola, manga e sapoti contribuiram para a melhoria do indice de estratificacao deste solo.

Produção e qualidade de frutos de tomateiro cultivado em substrato com zeólita

Yield and fruit quality of tomato grown in substrate with zeolite We evaluated yield and quality of tomato fruits, cv. Finestra, grown in a zeolite substrate enriched with N, P and K. Treatments comprised four levels (20; 40; 80 and 160 g per pot) of zeolite enriched with H 3 PO 4 /apatite, KNO 3 and KH 2 PO 4 , and a control grown in a nutrient solution. Fruit production, firmness, total soluble solids, pH, titratable acidity and ascorbic acid were evaluated from 80 to 90 days of plant cultivation. Nutrients supplied through the mineral zeolite enriched with N, P and K was an adequate alternative to increase the production. Higher fruit production was obtained with addition of P and K and higher zeolite dosis (160 and 80 g per pot). Fruit production was 11% and 17% higher when compared to the plants grown in nutritive solution (check treatment). Positive effects were observed in P-enriched zeolites in relation to fruit firmness, and negative effects over fruit pH. Fruit firmness varied 104% among treatments, from 7.06N (ZNK 160) to 14.38N (ZPK 40). The increase of potassium availablity increased the ascorbic acid levels of the fruits.