A series of nitrogen management experiments have been conducted over the past 11 years around the state to develop and refine fertilizer nitrogen (N) recommendations for irrigated desert cotton production. Stability analysis was used to summarize the data and to determine which of the four treatment regimes is most stable over a range of environments. Results indicate that the feedback treatment (treatment 3) was the most stable treatment for both Upland and Pima cottons and provided the best probability for a higher yield under high yielding environments. The untreated control treatment (treatment 1) was the least stable over a wide range of environments. These results further validate the ‘feedback’ approach to management of fertilizer N.

Proper timing of fertilizer N applications in relation to crop uptake can serve to improve fertilizer efficiency in irrigated cotton. Earlier research has identified an optimum application window extending from the formation of first pinhead squares to peak bloom, which corresponds well with maximum crop uptake and utilization. Field experiments were conducted at the University of Arizona Marana Agricultural Center (Grabe clay loam soil) utilizing sidedress applications of ammonium sulfate with 5-atom % 15-N at pinhead square, early bloom, and peak bloom at a rate of 56 kg N/ha. The objective was to compare relative efficiencies in terms of fertilizer N uptake and recovery among these three times of application. Results indicate that all treatments averaged approximately 80% total fertilizer N recovery. Of the fertilizer N that was recovered, approximately 40 % was taken up by the plants and 60 % recovered in the soil, primarily in the top 60 cm of the soil profile.

A laboratory study was initiated to investigate the potential loss of fertilizer nitrogen (N) through volatilization at four different temperatures (25, 30, 35, and 40°C) out of irrigation waters collected from a number of Arizona locations. Complete water analysis was conducted on each of the water samples. A 300 ml volume of each water was placed in 450 ml beakers open to the atmosphere in a constant temperature water bath with 10 mg of analytical grade (NH₄)₂SO₄ added to each sample. Small aliquots were drawn at specific time intervals over a 24 hour period and then analyzed for NH₄⁺-N concentrations. Results showed potential losses from volatilization to be highly temperature dependent. Total losses (after 24 hours) ranged from 30-48% at 25°C to over 90% at 40°C. In this study where (NH₄)₂SO₄ was used as the N source, the initial concentration of SO₄⁻-S in the solution had a repressive effect on volatilization due to the decreased availability of free NH₄⁺ in waters with high initial SO₄⁻-S concentrations due to the formation of complex ion pairs (NH₄SO₄⁻). It was also observed that at lower temperatures complexation and ion pair formation affected volatilization of NH₃ by reducing the NH₄⁺ activity in solution and thereby reducing NH₃ volatilization. Potential volatilization loss of fertilizer N from these irrigation waters was found to be significant and should be considered when making decisions regarding fertilizer N applications for crop production in Arizona.

Ironite and phosphorus were applied as a combined treatment and also individually to plots planted to long and short staple cotton to find their effect on crop development and lint yield. A statistically significant increase in lint yield was seen with 14 pounds of Ironite and 200 pounds of 16-20-0 per acre compared with the untreated check in the short staple plots. An increase in long staple yield was observed as the Ironite treatment increased from 7 to 28 pounds per acre when coupled with 200 pounds of 16-20-0. Few differences were seen between treatments in any of the plant mapping variables measured or with HVI values. More research and an economic analyses are needed to determine if this would be a recommended procedure in the Safford valley.

A two site evaluation of a calcium (Ca²⁺)-based soil conditioner was conducted during the 1999 cotton season. The two locations included one at the Maricopa Agricultural Center (MAC) in Maricopa, AZ and the other was on a grower-cooperator field in Tacna, AZ. Both studies involved the use of CN-9, a Ca-nitrate solution with 9% nitrogen and 11% Ca. At MAC theCN-9 solution was sprayed over the seedbed post planting but prior to the first water-up irrigation. At the Tacna site CN-9 was applied in a sidedress application at planting. Routine plant measurements were taken throughout the duration of both studies and lint yield estimates were made at each location at the end of the season. No significant differences due to the application of CN-9 were detected in any data collected.

Two soil amendments, Agriblend Plus and Superfloc A-836, were applied to cotton beds prior to planting at rates of 5, 10, 15 and 20 pounds per acre, incorporated and planted to short staple (DP 655BR) or long staple (HTO) cotton. The experimental plots were fertilized, irrigated and managed in a manner to produce optimal cotton yields. No statistically significant yield increases were seen from any of the treatments, even though a few interesting trends were observed. The report contains observations on plant mapping and lint quality data, in addition to yield data.

No description available.

O eucalipto apresenta bom crescimento em solos com alta acidez trocável e ativa, sendo a calagem uma prática realizada com o objetivo de fornecer Ca2+ e Mg2+. No entanto, o seu efeito fica restrito à camada superficial do solo devido à baixa solubilidade dos constituintes neutralizantes. A aplicação de gesso agrícola promove a movimentação de Ca2+ e SO4-2 no perfil do solo, possibilitando a melhora do subsolo para favorecer o crescimento radicular. A maioria das plantações de eucalipto no Brasil é estabelecida em solos de baixa fertilidade, verificando-se respostas significativas à fertilização com o fim de garantir a sustentabilidade da produção a longo prazo. O objetivo do presente estudo foi avaliar o crescimento da parte aérea e radicular do eucalipto em resposta à fontes e métodos de aplicação de cálcio em um Neossolo Quartzarênico. Para tal fim, foram mensurados: i) os teores de cálcio, magnésio e enxofre no solo e nas folhas; ii) a densidade de raiz fina (DRF) por biomassa ao longo do perfil e a umidade no solo, e; iii) o crescimento em altura e no diâmetro à altura do peito das árvores de Eucalyptus. A fertilização com calcário dolomítico e calcário calcinado em faixa promoveu aumento nos teores de Ca2+ e Mg2+ trocáveis no solo, especialmente nas camadas superficiais. Os teores foliares de Ca, Mg, K e S encontram-se na faixa adequada nas três datas de amostragem. O volume de tronco das árvores foi superior com a aplicação do calcário dolomítico em faixa comparativamente à aplicação de calcário dolomítico em área total ou incorporado. A mistura de calcário dolomítico com a maior dose de gesso aumentou os teores Ca2+ e Mg2+ trocáveis no solo nas camadas superficiais. A aplicação de gesso aumentou expressivamente os teores de SO42- abaixo dos 40 cm de profundidade. A DRF foi superior com a ausência da aplicação das fontes de cálcio. Com a aplicação de gesso agrícola misturado com calcário dolomítico se obteve um volume de madeira similar à aplicação de calcário dolomítico. / Eucalyptus plantations have a good development in soils with high exchangeable and active acidity, therefore, being the liming an activity done with the goal of providing Ca2+ and Mg 2+. However, its effect is restricted to the surface layer due to the low solubility of neutralizing constituents. The application of gypsum promotes the movement of Ca2+ and SO4-2 in the soil profile providing a more adequate root growth. Most eucalyptus plantations in Brazil were established in soils of low fertility, verifying significant responses to fertilization in order to ensure the sustainability of long-term production. The aim of this study was to evaluate the nutrition and aerial and root growth of eucalypts in response to different sources and methods of application of calcium in a Quartzipsamment. It was measured: i) calcium, magnesium and sulfur levels in soil and leaf; ii) Fine root density along the profile and soil moisture; iii) Growth in height and DBH of E. urophylla plantation. The fertilization with dolomitic and calcitic limestone in furrows promoted an increase in Ca2+ and Mg2+ levels in the soil, especially in surface layers. The Ca2+ and Mg2+ foliar levels found in the good range in three times. The volume of eucalypts was increased with dolomitic limestone in furrows comparatively broadcasted distribution and incorporation of dolomitic limestone. The mix of dolomitic limestone and the high gypsum level increases Ca2+ and Mg2+ levels in the soil in surface layers. Gypsum increases SO42- levels below 40 cm deep. The fine root density was higher without calcium fertilization. The volume wood with gypsum more dolomitic limestone applied was similar compared with dolomitic limestone applied.

Este trabalho teve o objetivo de propor uma metodologia adequada ao diagnostico nutricional e à avaliação da fertilidade do solo, dentro do contexto do balanço nutricional da cultura do plátano (Musa AAB subgrupo plátano cv. Hárton) no Sul do Lago do Maracaibo, Venezuela. O procedimento inicial foi, estratificar a área de amostragem por series semelhantes de solos da região. Desta maneira, selecionaram-se quatro lavouras com um histórico de melhor rendimento, na serie de solos de texturas francas. Em seguida fez-se a amostragem completamente ao acaso, entre os meses de julho a dezembro dos anos 2000 e 2001. O tamanho da amostra tirada por lavoura, foi de 30 unidades experimentais. Entretanto, por segurança acrescentaram-se cerca de 25%, dadas as possibilidades de perdas por rajadas de vento e chuva e outros infortúnios. A unidade experimental foi formada pela planta "mãe" e seu broto lateral "filho" em pleno desenvolvimento. Em cada unidade coletou-se a amostra foliar, na planta "mãe" de acordo a norma estabelecida pelo Método de Amostragem Internacional de Referencia (MEIR). Concomitantemente, tomou-se a amostra de solo, na faixa de adubação, em frente do "filho" em duas profundidades 0 - 20 cm e 21 - 40 cm. As amostras de folhas foram analisadas para N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, Mo e Zn. Nas amostras de solo se determinou-se pH, condutividade elétrica, matéria orgânica, areia, silte, argila, P, K, Ca, Mg, S, B, Cu, Fe, Mn e Zn. Os dados foram avaliados por analises de regressão com as combinações lineares dos componentes principais, regressão múltipla e obtenção da media aritmética das plantas com maior rendimento. Os resultados demonstraram que o modelo de regressão das combinações lineares com o rendimento deu uma melhor avaliação e predição do rendimento do plátano Hárton, dentro do contexto do balanço nutricional. Com esse modelo, posteriormente estimou-se o rendimento e se separou a população em classes desde o menor até o maior rendimento. Observaram-se nos dados dos analises de solos e folhas, incrementos, decréscimos ou ausência da variação nas concentrações de nutrientes em relação com o rendimento. Isto permitiu realizar interpretações simultâneas das análises de solos e folhas sem a necessidade de valores de referência. Por conseguinte vê-se que o modelo de regressão do rendimento com as combinações lineares vai além do uso de valores de referência isolados, pois permitiu determinar e utilizar o balanço nutricional entre todas as variáveis estudadas. Os resultados assim obtidos, permitem que a metodologia utilizada, seja indicada como una proposta de interpretação dos resultados de análises de solos e folhas. / The aim of this work is to suggest an adequate methodology for the evaluation of the nutritional status and of the fertility of soil for plantain grown in the South of Lake Maracaibo, Venezuela. Initially the area to sample was split into similar soil series. Four high yielding plantations were selected within a soil series of intermediate texture. Afterwards a random sampling was carried out from July to December 2000 and 2001. The sample per plantation had 30 experimental units, plus 25 % for safety reasons, since losses could occur due to weather conditions and other adverse factors. The experimental unit consisted of the "mother" plant and its fully developed "daughter". In each unit leaf sampling was done according to the "Method of International Sampling for Reference"(MEIR). Soil Samples were colleted in front of he daughter in the fertilization band at the depths of 0-20 and 21-40 cm. Leaf samples were analysed for N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, Mo and Zn. pH, conductivity, organic matter, sand, silt, clay, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn were determined in the soil samples. Data were evaluated by regression analysis with the lineal combinations of the main components, and by multiple regression. Results have shown that the regression model of the lineal combination with yield gave a better evaluation and prediction of the plantain crop, within the context of nutritional balance. This, on its turn allowed for the assessment of yield and for the separation of the population in yield classes. It was possible to observe both in the soils and leaves concentrations of nutrients related and not related to yield. It was possible, therefore, to conduct simultaneous interpretation of soil and leaf analyses obviating the need for reference values. The model of regression of yield against lineal combinations goes farther the than the isolated reference values since it allowed for the determination and utilization of nutritional balance among all variables. This methodology could be proposed for the interpretation of the results of soil and plant analyses.

Resumo: Suprir a demanda de alimento para mais de 6 bilhões de pessoas promovendo agricultura de forma sustentável é o desafio do novo milênio. O biocarvão (BC), ingrediente que proporciona ao solo capacidade de reter matéria orgânica e nutrientes, pode ser uma ferramenta de grande importância na busca de soluções para esse desafio. Portanto, entender o efeito do BC sobre o comportamento da matéria orgânica (MO) e o ciclo do fósforo inorgânico (Pi) em solo degradado foram os objetivos deste trabalho. A taxa de mineralização e o teor de carbono total foram monitorados nas misturas de solo degradado + 35%BC + doses de MO iguais a 0, 10, 40, 70 e 100 t ha-1, nos tempos 0, 80, 160, 240 e 320 dias de incubação em estufa. Reações de sorção e dessorção de Pi foram avaliadas nas misturas de solo degradado + 35%BC + doses de P com 0, 75, 150, 200 e 300 mg kg-1, no tempo 240 dias de incubação, além do controle com somente solo, para ambos os estudos. A adição de BC ao solo promoveu a mineralização da mistura; entretanto, o BC apresentou tendência à recalcitrância ao longo do período, dobrou o tempo de reação com o P tanto para as reações de sorção quanto dessorção, diminuiu a sorção de P do solo e dessorveu quantidades ideais para a maioria das culturas. O BC possui poder fertilizante, porém sua utilização deve ser assistida por possuir características químicas limitantes como pH e sais. Palavras chave: Fertilidade do solo, sorção, dessorção, mineralização. / Abstract: To supply the food demand for more than 6 billion people, promoting sustainable agriculture is the chellenge for the new milennium; the biochar (BC) ingredient that provides the ability to retain soil organic matter and nutrients can be an important tool to figure oout solutions for this challenge, thus, understand the effect of BC on the organic matter (OM) behavior and at inorganic phosphorus (Pi) cycle in degraded tropical soil has been our goal. The mineralization rate and total carbon content were monitored in mixtures of degraded tropical soil + 35% BC + OM doses, equal to 0, 10, 40, 70 and 100 t ha-1 at 0, 80, 160, 240, and 320 greenhouse incubation days. Pi Sorption and desorption Reactions were analysed in mixtures of degraded tropical soil + 35% BC + P rates of 0, 75, 150, 200, 300 mg kg-1, on 240 days of greenhouse incubation, beyond the control with soil by itself. The BC soil addition promote mineralization, however presented recalcitrance tendency in the incubation time, doubled the time of reaction with P for both the reactions of sorption and desorption, decreased P sorption and desorption of soil quantities ideal for most crops. The BC can act as a fertilizer, but its dosage should be well attended as it has the capacity to increase soil pH and salt. / Orientador: Iraê Amaral Guerrini / Coorientador: Nicholas Brain Comerford / Banca: Leonardo Theodoro Büll / Banca: Dirceu Maximino Fernandes / Banca: Newton Paulo de Souza Falcão / Banca: Rodrigo Domingues Barbosa / Doutor