P2O5 Rates Research Articles

Growth and nutrient contents in lowland rice due to phosphorus and potassium fertilization

ABSTRACT In order to reach an optimum and sustainable production, growers must know the fertilizing potassium (K) and phosphorous (P) application rates. The present study aimed to determine the rice development in response to combined rates of P and K, on Plinthaquults (380-400 g kg-1 of clay), under high and low fertility conditions, in the tropical lowland plain of the Araguaia river, Brazil. Three field experiments were performed, each one consisting of a completely randomized factorial block design, with three replications. Treatments included a combination of six K2O rates (0 kg ha-1, 30 kg ha-1, 60 kg ha-1, 90 kg ha-1, 120 kg ha-1 and 150 kg ha-1) with six P2O5 rates (0 kg ha-1, 30 kg ha-1, 60 kg ha-1, 90 kg ha-1, 120 kg ha-1 and 150 kg ha-1). No interaction effect between P and K rates was observed for the evaluated variables in any fertility level/year. Phosphorous application under low fertility conditions, as well as K under high fertility conditions, affect overall crop nutrition, tillering capacity, yield components and grain yield of lowland rice, though no effects were observed due to the P application in high fertility soils and K in low fertility soils. Under high fertility conditions, the grain yield increment rate due to the K application was 4.04 kg ha-1, whereas in the low fertility areas, such as recently cleared fields, a maximum yield of 7,161 kg ha-1 was achieved by applying 140 kg ha-1 of P.

English

The development of production technologies, such as greenhouses, was highlighted in the growth of horticultural crops. However, these products are often offered without basic instructions to farmers who can generate financial losses. One outstanding production technology is substrate cultivation, which would be very useful in the cultivation of protected plants. Like this, in order to evaluate the effects of different doses of phosphorus on the production of tomato groups grown in substrate under greenhouse conditions, a randomized complete block design was used in a 2 x 5 factorial scheme, with two tomato groups: Santa Cruz "Debora Max" and Cherry "Coco" x five rates of P2O5 (0; 33; 66; 99 and 132 g; 10 L of nutrient solution) with four replicates. The results showed that the electrical conductivity inside the Slabs is not homogeneous, being recommended to wet the substrate inside the slabs, before the planting to reduce the electrical conductivity. In relation to phosphorus efficiency, the highest tomato yield was for the 6.6 g L-1 phosphorus dose for the two Santa Cruz and Cherry groups. The main advantage of using slabs in tomatoes is the efficiency of the phosphorus used in the first planting.   Key words: Lycopersicon esculentum, substrate, slabs, phosphorus, fertilization.

Protein, Calcium, Zinc, and Iron Contents of Finger Millet Grain Response to Varietal Differences and Phosphorus Application in Kenya

This study was carried out to investigate the influence of phosphorus fertilizers on the concentrations of nutrients, particularly calcium, protein, zinc, and iron in finger millet grains grown in different agro-ecologies in Kenya. The on-station experiments were carried out at Kiboko (Eastern Kenya), Kakamega, and Alupe (Western Kenya) in 2015 during the short and long rainy seasons. The trials were laid out in a randomized complete block design (RCBD) in a 4 × 3 factorial arrangement with three replicates. The treatments comprised of four levels of phosphorus (0, 12.5, 25.0 and 37.5 kg ha−1 P2O5) and three finger millet varieties (U-15, P-224 and a local variety). Application of phosphorus significantly (p ≤ 0.05) increased the protein content of finger millet grain in varieties in all the three sites. Variety U-15 had the highest protein content (11.0%) at 25 kg ha−1 P2O5 with the control (zero P) on variety P-224 eliciting the lowest (4.4%) at Kiboko. At Kakamega, the 25 kg ha−1 P2O5 treatment with U-15 variety had the highest protein content (15.3%) while the same variety at 12.5 kg ha−1 P2O5 rate elicited the highest protein content (15.0%) at Alupe. Phosphorus application significantly enhanced the nutritional quality of finger millet grains specifically protein, calcium, iron, and zinc. Variety P-224 had the highest calcium content in all sites and highest iron content at Kakamega while the local varieties had the highest zinc content in all sites. The varieties responded differently to each quality component but generally, based on the protein content, the 25 kg ha−1 P2O5 is recommended.

Response of Two Wheat Cultivars to Nitrogen and Phosphorus Fertilizer Rates

Two field experiments was carried out at the Experimental Farm of Faculty of Agriculture, Kafrelsheikh University - North Nile Delta, Egypt, during the two successive winter seasons of 2014/2015 and 2015/2016, to investigate the effect of different nitrogen rates (60, 120, 180 and 240 kg N/ha) and phosphorus rates (0, 36 and 72 kg P2O5/ha) on yield and yield attributes of two bread wheat cultivars (Misr 2 and Giza 168) grown on clay soil conditions. Misr 2 was higher than Giza168 in values of number of days to heading, plant height, number of fertile tillers in both seasons and number of grain /spike, biological yield, grain yield and straw yield in the first season. Giza 168 recorded the highest values for 1000 grain weight and harvest index in the first season. Fertilizing with 240 kg N/ha resulted the highest values of yield attributes and significantly exceeded other studied levels (60, 120 and 180 kg N/ha). Application of 240 kg N/ha recorded the highest values of grain and straw yields (7.430 and 6.514 t/ha) and straw (12.071 and 10.119 t/ha) in the first and second seasons, respectively. P2O5had significant effect on most characters under this study. Increases P2O5 rates increased all traits except heading date and harvest index, where the inverse was true P2O5. Fertilizing with 72 kg P2O5/ha resulted the highest values of grain yield (6.564 and 6.749 t/ha) and straw yield (10.110 and 11.062 t/ha) in both seasons. Respectively. Fertilizer with 240kg N/ha and 72 kg P2O5/ha recorded the highest values for all traits in both seasons.

Remaining phosphorus content to determine phosphorus availability of the soils in Rio Grande do Sul

Abstract: The objective of this work was to evaluate remaining P compared with soil clay content as a P buffer index to classify P extracted by the Mehlich-1 (M1) and Mehlich-3 (M3) methods in soils from the state of Rio Grande do Sul, Brazil. The experiment was carried out in a completely randomized design with five P2O5 rates (0, 50, 100, 200, and 400 mg kg-1) and two sucessive corn crops, and three replicates, in 20 representative soils of the state. P extracted by M1 and M3 before crop planting was adjusted to P contents in biomass, considering soil buffer capacity. The division of soils into different buffering classes, based on soil clay or remaining P, improved the capacity of estimating soil available P of both methods. However, there was no difference among the correlation coefficients obtained by classifying soils according to the evaluated indexes (remaining P or soil clay) for both M1 and M3 methods. Remaining P is a viable alternative to replace soil clay content to classify soil P extracted with the M1 and M3 methods.

Plantas de cobertura e qualidade química e física de Latossolo Vermelho distrófico sob plantio direto

The study aimed to evaluate the influence of species of cover crops on chemical and physical soil properties. The survey was conducted during the winter of 2010 and 2011 in Selviria, Mato Grosso do Sul State, Brazil. The experimental design was a randomized block in a split plot with four replicates. The plots consisted of: millet, sun hemp, pea, velvet bean, millet + pigeon pea, millet and millet + crotalaria, and mucuna fallow. The subplots were represented by the absence of phosphate fertilizers and P2O5 rates (60, 90 and 120 kg ha-1) in the form of monoammonium phosphate (MAP). The subplots that have not received phosphate fertilizer chemical and physical soil properties were analyzed. The species used as cover caused changes in the chemical and physical properties of the soil. The soil maintained with millet + black mucuna presented the highest values of P and Ca, on millet higher values of OM, pigeon higher values of K, and those under the consortium millet + pigeon had higher concentrations of Mg. The soil maintained with millet Presented lower values of density and higher values of porosity.

Agromorphological Performance and Character Association of Finger Millet under Varying Phosphorus Regimes

Finger millet production on more than 30% of world arable land is limited by P availability and more than 70% in the semi-arid and marginalized areas which covers most of the Sub-Saharan Africa. Phosphorus is one of the most important elements significantly affecting plant growth and metabolism. Three finger millet varieties (U-15, P-224 and Ikhulule) were evaluated under four P fertilizer levels (0, 12.5, 25 and 37.5 kg ha-1 P2O5) at the International Crops Research Institute for the Semi-Arid Tropics Station, Alupe and the Kenya Agricultural and Livestock Research Organization Station, Kakamega during the long and short rainy seasons of 2015 with the aim of determining their agromorphological response and trait associations. The on-station experiments were laid out in Randomized Complete Block Design in factorial arrangement with three replications. The statistical analysis of phosphorus levels and variety exhibited significant differences (P<0.05) to stand vigor, plant height, leaf blade length, number of leaves and lodging. The results revealed that application of 25 kg ha-1 P2O5 rate led to the tallest plants (65.0 cm), longest leaf blades (58.0 cm) and highest number of leaves per plant (16) at Alupe site while 37.5 kg ha-1 P2O5 rate eliciting the tallest plants (58.79 cm), longest leaf blades (51.44 cm) and highest number of leaves per plant (13) at Kakamega site. The highest rate led to the greatest vigor in both sites for both seasons while the control had the poorest vigor. Variety P-224 showed the highest lodging count with 32 out of 246 plants per experimental unit during the rainy season at Kakamega. The unit increase in grain yield was positively and significantly correlated with increased values of the harvest index (r=0.375), number of leaves (r=0.393) and plant height (r=0.431) but negatively and significantly correlated to the 1000-grain mass (r=-0.578) and lodging (r=-0.233). The best phosphorus treatment for most of the parameters was 25 kg ha-1 P2O5 at Alupe while maximum levels of the study parameters were realized under the 37.5 kg ha-1 P2O5 rate at Kakamega.

Finger Millet (Eleusine coracana) Fodder Yield Potential and Nutritive Value under Different Levels of Phosphorus in Rainfed Conditions

Scarcity of fodder is the major limiting factor for increasing livestock production in Kenya. With rising energy costs and declining water levels in the semi-arid tropics and sub-tropics, crops that use less water like finger millet could become an alternate fodder crop. The fodder potential of three finger millet varieties (U-15, P-224 and a local check) were evaluated under four P fertilizer levels (0, 12.5, 25 and 37.5 kg ha-1 P2O5) at three sites in Kenya for two cropping seasons. The trials were laid in randomized complete block design in factorial arrangement and replicated three times. A maximum of 28,189 kg ha-1 fresh stover yield was realized in the 25 kg ha-1 P2O5 treatment and consequently 11,616 kg ha-1 dry stover yield. The 25 kg ha-1 rate elicited the highest fresh stover yield at Kakamega and Alupe for both seasons while at Kiboko a linear increase was observed on the stover yield with increasing rates where the highest rate had more than 15% yield compared to the control. The varieties also showed significant differences in all the sites with the local variety, Ikhulule, showing the highest fresh and dry stover yield at Kakamega and Alupe peaking at 28,852 and 12,826 kg ha-1 fresh and dry stover yields respectively. Interactions between variety and phosphorus rates were revealed on the crude protein content of the finger millet stover. At Kiboko, the highest crude protein (11.0%) on varieties P-224 and U-15 was exhibited at the highest rate while on the local variety, Ekalakala, the highest protein (10.9%) was realized at the 25 kg ha-1 P2O5. At Kakamega and Alupe, the highest protein was observed on the local variety, Ikhulule at 12.5 kg ha-1 P2O5 rate with variety P-224 and U-15 showing the highest at the 25 and 37.5 kg ha-1 P2O5 respectively. Therefore, finger millet can provide a unique opportunity to improve the availability of fodder to smallholder livestock farmers.

Nitrogen and Phosphorus Uptake and Partitioning in Finger Millet as Influenced by Phosphorus Fertilization

Finger millet (Eleusine coracana) production in Eastern Africa remains low due to a variety of factors including soil nutrient depletion. As intensive row-crop production evolves, improvements in managing soil nutrient quantity and availability of less renewable nutrients like P becomes increasingly important. The yields in Kenya are typical of low input systems ranging below 1.0 t ha-1 against a potential of 5.0 t ha-1 in a season. In an attempt to overcome this constraint, On-station experiments were conducted at the Alupe research station during the long and short rain seasons of 2015 to investigate the influence of phosphate fertilizer rates (0, 12.5, 25 and 37.5 kg ha-1 P2O5) on nutrient uptake and partitioning in finger millet. Partitioning of N and P was significantly influenced (P 30%) while the least to the roots (<19%). Variety U-15 had the greatest partitioning of nitrogen to the grains while the local variety, Ikhulule had the least. Application of phosphorus led to increase in the nitrogen and phosphorus uptake in finger millet with the most in the grains with a maximum of 106.5 kg ha-1 on the 37.5 kg ha-1 P2O5 rate during the short rains while the roots had the lowest uptake with 16.9 kg ha-1 and 22.1 kg ha-1 in the long and short rains seasons respectively on the control. This study on nutrient use provides an opportunity to further improve P fertilization to specific rates in relation to crops needs as farmers will be assured of greater yields, profitable and sustainable production. Limited use of P fertilizer restricts the uptake of phosphorus and nitrogen as well as the balance in partitioning and recommends application of 25 kg ha-1 P2O5 with improved varieties.

Phosphate fertilization over the accumulation of macronutrients in cauliflower seed production

abstract Considering the scarce information on nutrient extraction by plants for seed production within vegetable crops, as well as the effect of fertilization over extraction, studying nutrient accumulation in different plant parts under varied fertilization rates is necessary. This study aimed to evaluate the influence of phosphate rates on macronutrient accumulation in cauliflower plants during seed production. Five phosphate rates were studied (0, 300, 600, 900 and 1200 kg/ha P2O5), in a randomized complete block design, with four replications. Accumulation of nutrients in the different plant parts was evaluated at the end of the cycle (vegetative and reproductive, the latter divided in seeds and inflorescence). Data were submitted to analysis of variance and regression. Considering only the seeds, a quadratic effect was obtained for the accumulation of all macronutrients, with maximum estimated for rates between 858 and 952 kg/ha P2O5. Considering the whole plant (total accumulation), a linear increase for P, Ca and S was obtained the higher the P2O5 rates, while the effect was quadratic for N, K and Mg accumulation. The total nutrient accumulation descending order was: K&gt;N&gt;Ca&gt;S&gt;P&gt;Mg, and considering only the seeds was: N&gt;S&gt;K&gt;P&gt;Ca&gt;Mg, S being highlighted as the second most accumulated nutrient in the seeds.

Phosphorus Effects on Biomass Accumulation and Nutrient Uptake and Removal in Two Potato Cultivars

Information on the effect of P fertilization on nutrient uptake and removal by potato (Solanum tuberosum L.) cultivars is required for proper soil nutrient management. This study was performed to evaluate how dry matter (DM) accumulation and partitioning, the uptake of nutrients, and their allocation to the tubers and removal in potato cultivars (Agata and Mondial) are affected by the P fertilization rates (0, 125, 250, 500, and 1000 kg ha−1 P2O5) placed in the furrow at planting as triple superphosphate. An experiment was conducted over 2 site‐years in loam clayey Oxisols with low P availability in São Paulo State, southeastern Brazil. Both cultivars exhibited very similar DM accumulation, tuber yield, and nutrient uptake and allocation to the tubers when P was not supplied at planting. Phosphorus fertilization greatly increased the DM accumulation and nutrient uptake and removal of both cultivars. The cultivar Mondial was more responsive to P fertilization and its uptake and removal of N, P, K, Ca, Mg, B, and Zn were greater than for Agata. Application rates of P2O5 exceeding 500 kg ha−1 only increased the uptake of Ca and P and the removal of P, but the plant growth and tuber yield did not increase above this P rate. The harvest index (HI) and the nutrient allocation to the tubers were not affected by the P rates and barely differed between the cultivars. Differences in nutrient removal between the cultivars were more related to the tuber DM yield than the HI. Potato biomass accumulation is positively related to an adequate P supply. Phosphorus fertilization greatly increases nutrient uptake and removal of potato cultivars. The cultivar Mondial is more responsive to P fertilization than Agata. The harvest index and nutrient allocation to the tubers are not affected by P application rates. Nutrient removal by each potato cultivar is more related to the tuber yield than the harvest index.

Phosphorus Influence on Plant Tissue Nitrogen Contents and Yield Attributes of Finger Millet Varieties in Semi-arid Region of Kenya

The experiment was conducted with the aim of evaluating the effect of differential levels of P on finger millet accumulation of N and yield components. On-station experiments were conducted at the KALRO-Kiboko crops research station in Makueni County during the short and long rains of 2014 and 2015 respectively. There were 4 levels of P (0, 12.5, 25 and 37.5 kg ha-1 P2O5) and three varieties (U-15, P-224 and Ekalakala). Ekalakala was the local check while 0 kg/ha P2O5 was the control. The trial was laid out in a randomized complete block design and fitted in factorial arrangement with three replicates given a total of 36 plots. Soil sampling was at a depth of 0-30 cm on all the plots and analytical results showed moderately available P but very low N, organic carbon and zinc. Significant differences (P=.05) were observed between the phosphate levels on the nitrogen contents in plant parts with the control showing the lowest N accumulation of 4.95% and 4.90% for the short and long rains respectively while the 25 kg ha-1 P2O5 rate had the highest with 5.66% in the short rains and 5.14% in the long rains. The stem contained the highest nitrogen content while the roots had the lowest. Phosphate rates did not have significant influence on the yield components except the finger width while the varieties varied significantly (P=.05) on the productive tillers, panicle number, grains per spikelet and the harvest index. Variety U-15 had the highest yield for both seasons with a maximum of 3410 kg ha-1 for the short rains. The newly released variety (U-15) responded well to moderate P supplemented at 25 kg ha-1 P2O5 thus can efficiently utilize N in soils with low N like in Makueni and is highly recommended. The optimal P for the yield and N accumulation was 25 kg ha-1 P2O5 and beyond this point the P would not be translated to profitable yield but a loss to the farmer in the short run.

Effect of Phosphate Levels on Soil Rhizosphere Nutrient Balances and Finger Millet Yield

Soil infertility is one of the main factors leading to low finger millet production in the semi-arid tropics of Kenya. About 50-80% of P applied as fertilizer is adsorbed by soil and the amount of P needed to achieve maintenance of its adequate status and influence on other soil properties has not been well documented. An on-station experiment was therefore conducted at the KALROKiboko research station during the 2014 long and 2015 short rain seasons to investigate the influence of phosphorus rates on soil rhizosphere chemical properties and yield of three finger millet varieties. The experiment was laid out in a Randomized Complete Block Design in factorial arrangement and replicated three times. There were four P levels (0, 12.5, 25 and 37.5 kg ha-1 P2O5) and three varieties (U15, P-224 and local check-Kat FM1). Phosphorus application reduced the soil pH significantly for both seasons with the 37.5 kg ha-1 P2O5 rate eliciting the greatest pH from 9.26 to 7.90 (1.36 units) during the long rain season. As expected, soil phosphorus increased with the highest rate with 11 ppm during the long rain season and 9 ppm for the short rains. The organic carbon increased by 0.28% for the long rain season on the 25 kg ha-1 P2O5 rate while the highest rate increased total N by 0.05%. The 25 kg ha-1 P2O5 rate and U-15 indicated the highest yield for both seasons with a maximum of 3.71 t ha-1 realized during the short rain season. Monitoring change in soil nutrient status is important for prescribing P fertilization in order to maintain or replenish soil fertility. The application rate of 25 kg ha-1 P2O5 led to the optimal yields under the improved variety and hence the study recommends this rate.

Effect of Soil Nitrogen and Phosphorus on Early Development and Essential Oil Composition of Schinus terebinthifolius Raddi

Schinus terebinthifolius is a native Brazilian plant. It is wide-spread throughout Brazil and is popularly used as a medicinal plant. Research on this plant is encouraged by the Ministry of Health to investigate its therapeutic potential and to ensure its distribution in the National Health System. Thus, an experiment was carried out in Dourados-MS (22°11'53.8"S and 54°56'0.12"W) to evaluate the effects of nitrogen and phosphorus levels on early development, biomass yield and chemical composition of the essential oil of Schinus terebinthifolius. Five P2O5 rates (20, 120, 200, 280 and 380 kg ha−1) and five N rates (6, 36, 60, 84 and 114 kg ha−1) were used. Treatments were defined using the Plan Puebla III matrix, resulting in nine combinations of P2O5 and N levels, respectively (kg ha−1): 280 and 84; 280 and 36; 120 and 6; 120 and 36; 120 and 84; 200 and 60; 380 and 84, 20 and 36, and 280 and 114. The experimental design was a randomized block with four replications. Plants were harvested 105 and 213 days after transplanting. Phosphorus and nitrogen influenced plant height (174.65 cm), stem diameter (14.32 mm), fresh mass of leaves (169.67 g plant−1) and dry matter of leaves (51.01 g plant−1). Essential oil content (0.16 ml plant−1) was also influenced. The major constituents of the essential oil were α-pinene (15.20-15.56 %), limonene (13.58-14.12 %), sabinene (8.98-9.17 %), β-pinene (8.18-8.99 %), α-copaen (8.98-9.49 %) and z-zalvene (8.56-9.19 %). Thus, we recommend harvesting 213 days after transplanting and growing plants with 249.15 P2O5 and 98 N (kg ha−1).

Qualidade de tubérculos de batata da cultivar 'Atlantic' afetada pela adubação fosfatada

To evaluate the influence of phosphorus (P) fertilization on the potato tuber quality of the cultivar 'Atlantic' experiments were conducted in soils with medium (36 mg dm-3) and high (70 mg dm-3) P availability. The treatments consisted of five P2O5 rates (0, 125, 250, 500, and 1,000 kg ha-1). The experiments were conducted in a randomized block design, with four replications. Only in soil with medium P availability, the phosphorus fertilization decreases protein, but increases starch content of the tubers until rate of 595 kg ha-1 P2O5. Phosphorus fertilization increases the tuber size and marketable yield, but in a more expressive and until higher rates in soil with medium P concentration, in which the influence of tuber size on marketable yield is higher. In two conditions of P availability, the phosphorus fertilization has greater influence on the tuber size and the production of processed material (dry matter yield of tubers) than on the quality characteristics of tubers that influence in the quality frying.

Efeito da adubação fosfatada na produção de sementes de soja

O fósforo pode contribuir com o aumento de qualidade das sementes produzidas e incrementar a produtividade de grãos. O objetivo deste trabalho foi avaliar o efeito da adubação fosfatada sobre a qualidade, a composição química e a produtividade das sementes de soja e, a produtividade de grãos em lavoura estabelecida partir dessas sementes. Foram realizados dois ensaios. No Ensaio 1 avaliaram-se os seguintes tratamentos: T1 - controle, semeadura sem P2O5; T2 - 50% a menos que a dose de P2O5 recomendada com base na análise do solo; T3 - 100% da dose de P2O5 recomendada; T4 - 50% a mais que a dose de P2O5 recomendada; e, T5 - 100% a mais que dose de P2O5 recomendada. Após a colheita foram determinados o número de sementes e de legumes por planta, a produtividade, a germinação, a viabilidade e o vigor por meio do teste tetrazólio, a composição química e a massa de mil sementes. No Ensaio 2, as sementes colhidas no Ensaio 1 foram semeadas e avaliou-se o número de legumes e o de grãos por planta e a produtividade. O delineamento experimental utilizado nos dois ensaios foi em blocos ao acaso, com cinco repetições. A adubação fosfatada proporciona maior vigor das sementes de soja, além de contribuir para o aumento de fósforo, ferro e zinco nas sementes produzidas. Sementes com maiores concentrações de fósforo em sua constituição contribuem para o aumento de produtividade da soja.

ADUBAÇÃO FOSFATADA E COMPACTAÇÃO DO SOLO: SISTEMA RADICULAR DA SOJA E DO MILHO E ATRIBUTOS FÍSICOS DO SOLO

Associadas aos benefícios no solo da semeadura direta, podem ocorrer a formação de gradiente vertical de fertilidade e a de uma camada compactada provocada pelo intenso tráfego de máquinas agrícolas, podendo modificar o crescimento radicular das culturas. O objetivo deste trabalho foi avaliar as doses e formas de aplicação da adubação fosfatada e a compactação do solo pelo tráfego de máquinas nos atributos físicos e no sistema radicular da soja e do milho nas condições da Chapada dos Parecis, MT. O estudo foi realizado em Latossolo Vermelho-Amarelo distrófico argiloso em delineamento em blocos casualizados, no esquema fatorial 2 × 4 × 4 e três repetições, sendo duas formas de adubação fosfatada (a lanço e no sulco), quatro doses de P2O5 (0, 50, 100 e 150 kg ha-1) e quatro níveis de compactação (PT0, PT2, PT4 e PT8 – semeadura direta com compactação induzida por tráfego de trator em zero, duas, quatro e oito passadas, respectivamente). O tráfego de máquinas ocasionou compactação do solo em semeadura direta, aumentando a densidade do solo (Ds) e resistência do solo à penetração (RSP) e reduzindo a macroporosidade e porosidade total, sem efeito da adubação fosfatada. A resposta das espécies à forma de adubação fosfatada foi diferenciada, não apresentando influência no crescimento radicular da soja. No milho, quando fornecida a lanço proporcionou maior área de raízes na camada de 0,00-0,05 m; e, quando no sulco, foram observadas entre as camadas menores diferenças na área radicular. Nas camadas de 0,05-0,10 e 0,10-0,20 m, a RSP de 1,48 e 1,84 MPa (Us = 0,28 m3 m-3) e Ds de 1,32 e 1,35 kg dm-3, respectivamente, proporcionaram redução de 19 e 27 % no diâmetro médio das raízes do milho e aumento de 110 e 49 % no diâmetro das raízes da soja.

Effect of Mineral Fertilization and Irrigation on Sunflower Yields

Among the cultures used for the production of biofuels, the sunflower is one of the most important. Although some information exists, the water and nutritional needs of sunflower in the north east of Brazil are not well known. To fill knowledge gaps, an experiment was carried out to evaluate the effect of nitrogen (N), phosphorus (P), potassium (K) fertilization and available soil water (ASW) on sunflower yields. The sunflower cultivar Embrapa 122-V2000 was subjected to 44 treatments on a completely randomized design generated by the Baconian Matrix with four rates of N (0, 60, 80 and 100 kg&middotha-1), four rates of P2O5 (0, 80, 100 and 120 kg&middotha-1), four rates of K2O (0, 80, 100 and 120 kg&middotha-1), and four available soil water (ASW) levels (55%, 70%, 85% and 100%) replicated three times. Urea was used as a source of N, triple super phosphate as P and potassium chloride as K. In all the experimental units was applied 2 kg&middotB&middotha-1 as boric acid. The components of production evaluated were dry matter of the head, total number of achenes, total achenes’ weight and 1000 achenes’ weight. The results of this research showed that nitrogen had a significant effect on the dry matter of the head, total number of achenes and total achenes’ weight. Phosphorus affected all production components and potassium affected the total number and the weight of achenes. With the exception of the 1000 achenes’ weight, all the production components of the sunflower increased with the increased ASW level influenced significantly at 0.01 level of probably the total number of achenes. The highest rates of N, P and K (100, 120 and 120 kg&middotha-1, respectively) and 100% of available soil water produced the highest production.

Adubação fosfatada no desenvolvimento de Hemerocallis fulva L.

In clayey Oxisol from the Brazilian Cerrado, where there is high P fixation, the phosphorus fertilization is necessary to increase the growth and flowering of ornamental plants. Thus, the objective of this study was to analyze the development of Hemerocallis as affected by phosphorus application in clayey Oxisol (Typic Haplustox). The experiment was conducted at the Gardening area of University Federal of Grande Dourados (UFGD) in Dourados-MS, Brazil. The experimental design was a randomized block with four replications. The treatments consisted of four P2O5 rates (0, 250, 500, 1000 kg ha-1) using simple superphosphate as source. The experimental unit was composed of one Hemerocallis fulva ‘Flore Pleno’ plant, grown in a plastic pot (5 liters). Phosphorus fertilization increased linearly the concentration of phosphorus in the soil; the plant had maximum absorption (5.26 g kg-1) with the calculated dose of 727 kg ha-1 P2O5. H. fulva has a root system that develops best under high availability of P, however, for aerial part, the maximum of shoots fresh mass (451.1 g) was obtained with 427 kg ha-1 of P2O5. Number of flower buds, flower diameter and height flower stalks were higher in the presence of phosphorus.

Evaluating Cenozoic equatorial sediment deposition anomalies for potential paleoceanographic and Pacific plate motion applications

If equatorial sediments form characteristic deposits around the equator, they may help to resolve the amount of northwards drift of the Pacific tectonic plate. Relevant to this issue, it has been shown that 230Th has been accumulating on the equatorial seabed faster than its production from radioactive decay in the overlying water column during the Holocene (Marcantonio et al. in Paleoceanography 16:260–267, 2001). Some researchers have argued that this reflects the deposition of particles with adsorbed 230Th carried by bottom currents towards the equator (“focusing”). If correct, this effect may combine with high pelagic productivity, which is also centered on the equator, to yield a characteristic signature of high accumulation rates marking the paleoequator in older deposits. Here we evaluate potential evidence that such an equatorial feature existed in the geological past. Seismic reflection data from seven meridional transects suggest that a band of equatorially enhanced accumulation of restricted latitude was variably developed, both spatially and temporally. It is absent in the interval 14.25–20.1 Ma but is well developed for the interval 8.55–14.25 Ma. We also examined eolian dust accumulation rate histories generated from scientific drilling data. A dust accumulation rate anomaly near the modern equator, which is not obviously related to the inter-tropical convergence zone, is interpreted as caused by focusing. Accumulation rates of Ba and P2O5 (proxies of export production) reveal a static equatorial signature, which suggests that the movement of the Pacific plate over the period 10–25 Ma was modest. The general transition from missing to well-developed focusing signatures around 14.25 Ma in the seismic data coincides with the mid-Miocene development of the western boundary current off New Zealand. This current supplies the Pacific with deep water from Antarctica, and could therefore imply a potential paleoceanographic or paleoclimatic origin. At 10.05–14.25 Ma, the latitudes of the seismic anomalies are up to ~2° different from the paleoequator predicted by Pacific plate-hotspot models, suggesting potentially a small change in the hotspot latitudes relative to the present day (although this inference depends on the precise form of the deposition around the equator). The Ba and P2O5 anomalies, on the other hand, are broadly compatible with plate models predicting slow northward plate movement over 10–25 Ma.