Two field experiments were conducted in Arizona in 2000 at two locations (Maricopa and Marana). The Maricopa experiment has been conducted for nine consecutive seasons; the Marana site was initiated in 1994. The purposes of the experiments were to validate and refine nitrogen (N) fertilization recommendations for Upland cotton. The experiments each utilized N management tools such as pre-season soil tests for NO₃⁻-N, in-season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location revealed a strong relationship between the crop fruit retention levels and N needs for the crop. This pattern was further reflected in final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive, N application regimes did not benefit yields at any location. In 2000, fruit retention levels were good and crop vigor was not excessive. The more conservative, feedback approach to N management provided optimum yields at both locations.

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.

Water colour is the naturally occurring yellow-brown 'tea like' discolouration which can be observed in freshwaters, and is typically composed of high molecular weight organic carbon. Water discolouration is a major problem for the water industry as over the past 30 years, water colour release has more than doubled, greatly increasing treatment costs and making land management a more feasible option for improving water quality. This project was developed in conjunction with Yorkshire Water Plc, to investigate the mechanisms of water colour production, and the implications that these mechanisms have for land management to improve water quality. In particular, the study aimed to identify the key relationships between drainage water quality and quantity, soil processes and vegetation type that are pivotal to the understanding of water discolouration.

Orientador: Ricardo Antônio Ferreira Rodrigues / Banca: Kuniko Iwamoto Haga / Banca: Flavio Ferreira da Silva Binotti / Resumo: A redução do espaçamento entrelinhas de semeadura, permitindo um melhor arranjo das plantas, aliada a diferentes densidades populacionais estão entre os fatores mais importantes na determinação da produtividade do milho. O trabalho objetivou avaliar a interceptação da radiação fotossinteticamente ativa (IRFA), as características agronômicas e a produtividade da cultura do milho submetido a diferentes sistemas de preparo de solo, espaçamentos entrelinhas e densidades populacionais. Os tratamentos constituíram-se de: dois sistemas de preparo de solo (convencional e plantio direto), dois espaçamentos entrelinhas (0,45 e 0,90 m) e cinco densidades populacionais (40.000, 55.000, 70.000, 85.000 e 100.000 plantas ha-1). O híbrido utilizado foi o DKB 390 PRO. O delineamento experimental utilizado foi em blocos casualizados no esquema fatorial 2 x 2 x 5 com quatro repetições. O aumento da densidade populacional resultou no aumento da produtividade de grãos, na altura de planta e na altura de inserção da espiga, e redução no diâmetro do colmo, comprimento de espiga, diâmetro da espiga, número de grãos por fileira, número de grãos por espiga, prolificidade e na massa de 100 grãos; o preparo convencional do solo proporcionou maior produtividade de grãos; a redução do espaçamento entrelinhas aumentou o diâmetro do colmo e a prolificidade e reduziu a altura de inserção da espiga. No estádio V10 verificou-se maior índice de área foliar (IAF) quando o espaçamento foi de 0,45 m e plantio direto, resultando em ajuste linear crescente em função do aumento da densidade. A maior interceptação da radiação fotossinteticamente ativa interceptada (IRFA) pelo dossel foi proporcionada pela utilização do espaçamento de 0,45 m. No pendoamento, foi verificado maior IAF no espaçamento de 0,45 m e ajuste linear crescente para o aumento da densidade, e em relação ao IRFA ocorreu ponto de máximo com 79.412 plantas ha-1. No... / Abstract: Reducing the spacing row of seeding, allowing a better arrangement the plants, combined with different population densities are some of the most important factors to determine the grain yield of maize. The study evaluated the interception of photosynthetically active radiation (PAR), the agronomic characteristics and the grain yield of maize cultivated under different tillage systems, row spacing and population densities. The treatments consisted in combination of two soil management (conventional and no-tillage), with two row spacing (0.45 and 0.90 m) and five population densities (40,000; 55,000; 70,000; 85,000 and 100,000 plants ha-1). The hybrid used was DKB 390 PRO. The experimental design was randomized blocks in a factorial 2 x 2 x 5 with four replications. The increased population density resulted in increased grains yield, in plant height and in ear insertion and decrease in stem diameter, ear length, ear diameter, number of grains per row, number of grains per ear, prolificity and the weight of 100 grains; the conventional soil management increased the grain yield; the reducing the spacing row increased the diameter of stem, the prolificity and reduced the insertion's height of ear. In stage V10 there was higher leaf area index (LAI) when used the spacing of 0.45 m and no tillage, occurred linear fit growing due to the increase in density. For photosynthetically active radiation intercepted by the canopy (IRFA) using the 0.45 m row spacing provided greater interception of sunlight. At tasseling, higher LAI was observed in spacing of 0.45 m and increasing linear adjustment for increased the density, in relation to the IRFA maximum point occurred with 79,412 plants ha-1. At flowering, LAI was greater for spacing of 0.45 m and occurred to the point of maximum with 76,449 plants ha-1, and the intercept was higher IRFA for spacing 0.45 m and for no-tillage with maximum point 79,096 plants ha-1 / Mestre

Orientador: Carlos Antonio Gamero / Banca: Sérgio Hugo Benez / Banca: Rubens Siqueira / Resumo: A cultura da soja é um dos mais importantes produtos agrícolas do país. O sistema de produção de soja predominante utiliza como forma de preparo do solo o uso de arados e grades, caracterizado pela intensa mobilização do solo podendo causar danos ambientais e degradação do solo. Como alternativa para solucionar esses problemas, indica-se a mínima mobilização do solo, mantendo resíduos vegetais na superfície do solo, favorecendo sua conservação. Com o objetivo de avaliar o desempenho agronômico de cultivares de soja recomendadas para o Estado de São Paulo em diferentes sistemas de preparo do solo, desenvolveu-se o presente trabalho,instalado e conduzido em campo experimental na Fazenda Experimental Lageado da Faculdade de Ciências Agronômicas da UNESP, Campus de Botucatu. O delineamento experimental foi em blocos ao acaso com parcelas subdivididas com quatro repetições. Os tratamentos resultaram da combinação de três sistemas de preparo do solo e dez cultivares de soja totalizando trinta tratamentos. Os três sistemas de preparo do solo foram: PR- preparo reduzido com escarificador, PC- preparo convencional com grade aradora e niveladora e PD- plantio direto sob vegetação de triticale dessecada com herbicida, foram instalados nas parcelas e as variedades de soja nas subparcelas. Os cultivares de soja foram: C1- IAC 18, C2- FT Abyara, C3- IAS 5, C4- Embrapa 45, C5- IAC 8.2, C6- FT Cometa, C7- Embrapa 133, C8- M.Soy 7501, C9- IAC 22 e C10- Engopa 315. Os resultados demonstram que os sistemas de preparo do solo não influenciaram: altura de inserção da primeira vagem, número de vagens, população inicial e final de plantas, número de grãos por vagem e peso de mil grãos e produtividade, influenciando apenas a altura de plantas. / Abstract: The soybean is the most important agricultural product of the country. The tillage system that predominates in this crop is the conventional tillage with plowing or heavy harrowing and the leveling harrowing characterized by intense mobilization of the soil causing damages to the environment and soil degradation. As an alternative to solve these problems a minimum or no soil mobilization is suggested maintaining vegetable residues in the surface on behalf of the soil conservation. In the seeds market there are lots of soybean cultivares regarding morphologic, physiologic and productivity characteristics. The present work was carried out with the purpose of evaluating the behavior of the soybean cultivares in different soil management systems recommended to the state of São Paulo. The experiment was installed and conducted in the Experimental Farm Lageado in the College of Agricultural Sciences, UNESP, Botucatu Campus. The experimental delineation utilized was the random block with subdivided plots in four replicates. The treatments were combination of three soil management systems and ten cultivares of soybean. The three management systems were: PC- conventional tillage with heavy harrowing and leveling; PR- reduce tillage with moulboard and PD- no tillage in the vegetation dried with herbicid were installed in the plots, the ten cultivares of the soybean were: C1- IAC 18, C2- FT Abyara, C3- IAS 5, C4- Embrapa 45, C5- IAC 8.2, C6- FT Cometa, C7- Embrapa 133, C8- M.Soy 7501, C9- IAC 22 e C10- Engopa 315 were installed in the subplots. The results demonstrated that the soil management practies did not influence the productivity, height of insert of the first shell, number of shells, initial and final population of plants, number of grain by shell and weight of one thousand grains, influenced only by the height of the plants. / Mestre