The estimated yield quadratic response was also reported for other crops. Rós et al. (2014) reported that sweet potato fertilized with chicken manure up to the rate of 12 t ha -1 presented maximum commercial yieldof tuberous roots (23.6 t ha -1 ) at the rate of 5.8 t ha -1 , with decrease in yield at higher rates of manure. Oliveira et al. (2001) verified that the addition of chicken manure to yam crop promoted yield increase up to the rate of 6.6 t ha -1 andyield reduction at higher rates. Therefore, the use of excessive amounts oforganic fertilizers results in a decrease of crop yield. Primavesi (2002) argued that excess NPK reduces nutrient absorption and can reach toxic levels, causing imbalance in the absorbed and metabolized macro and micronutrient concentrations, which results in yields lower than the plant potential when there is a ba- lance between the rates of absorption and metabolization. However, Rós et al. (2014) studying the same cassava variety as the present study, found that the rates up to 18 t ha -1 did not reduce yield, which indicates that for the those environmental conditions the amount of manure was not capable of damaging the crop.
The great challenge is to maintain this level, due to the intense SOM mineralization process, resulting from weather conditions, along with irrigation management. Furthermore, sandy textured soils have a higher organic matter decomposition rate, due to the smaller amount of variable-charge clay minerals, providing less physical protection oforganic matter. Chemical stability of aggregates in these soils is also affected by low Fe levels, favoring organic matter mineralization. Consequently, practices that promote SOM input and conservation are essential for the sustainability of these sandy soils. Increases in SOM by composts and other organic residues, with lower or higher values according to the climate andsoil conditions of each region, were also reported by other authors (Damatto Júnior et al., 2006; Clemente et al., 2012; Mugnai et al., 2012; Silva et al., 2013).
Researchers have shown that soil test levels for P, K and lime vary considerably within sugarcane (Corá et al., 2004; Souza et al., 2004; Johnson & Richard, 2005) and other crop fields (Kravchenko & Bullock, 2000), with coefficients of variation (CV) greater than 30%. Landell et al. (2003) evaluated the effectsof the subsurface chemical attributes of Oxisols on the yieldof some sugarcane clones, andof the cultivar RB72454 during the first, second and third cropping cycles. The authors verified, from multiple regression analyses, that in the third harvest yield variation for clones could be explained by two attributes: base saturation and phosphorus content. For the cultivar RB72454, 47% of that variation was explained by the sum of bases and the contents of calcium andorganic matter.
The soilchemical analysis data obtained for the 0.05-0.10 m depth indicated significant differences for the soil P concentrations among the cover crops (Table 5). The plots under black oat presented higher soil P concentrations than those under forage turnip. The low mobility and accumulation of P in the surface layers could also be connected with residue deposition, which favors the redistribution of the organic forms that are less susceptible to degradation (SANTOS; TOMM, 2003). Nevertheless, no effect of the increasing AS doses on the soil P was observed at any depth analyzed in 2007 and 2008, demonstrating that this element was only slightly influenced by fertilizer application.
Leguminous and grass cover crops have been successfully used to improve soilproperties in many region s (Lal et al. 1979). Beneficial effectsof crop residues onsoil surface under conservation tillage include increased water conservation andsoil aggregatio n (Lal 1976; Blevins et al. 1983). The ef fectiveness of cover crops in improving soil structure has been reported in many stud ies (Tisdall et al. 1979; Haynes and Beare 1997). Blanchart et al. (2004) studied the eff ects of grass roots onpropertiesof a degraded Vertisol and reported that restoration ofphysicalproperties was quicker and greater in treatments with plants than in treatments without plants. Plants also played a dominant role through rhizosphere effectsand possible carbon rhizodeposition. It has been shown that cover crops added organic matter to the soiland promoted soil faunal activity. Soilorganic matter has significant impacts onsoil physicochemical attributes. Organic matter also improves soil porosity and, therefore,
Also, the accentuated accumulation of P on no- tillage system was remarkable compared with other treatments. On the other hand, the lower ratios of Ca and K observed at the pasture or the medium ratios of these nutrients observed for conventional tillage probably occurred due to the losses caused by soil erosion and crop residues incorporation (Rheinheimer et al., 1998). In Brazil, many type ofsoil is phos- phate-limited for plant production. The larger inert reservoir of this mineral has been phosphate rock, but this reservoir is being increasingly tapped by the fertilizer industry. Usually, small and actively cycled reservoirs of phosphate are dissolved in living and dead organic matter. Most microbial P transforma- tions are performed as a transfer of inorganic to or- ganic phosphate or as transfer of phosphate from in- soluble, immobilized forms to soluble or mobile com- pounds (Atlas & Bartha, 1993). Therefore, the re- sults observed on the no-tillage system can be ex- plained by the fact that the soilon this system usu- ally provides a vertical deposition of crop residues, once it is not periodically revolved as well as it pre- sents high microbial activities (Table 1).
When compared with the original soil (TSMO), the treatments with moderate and high soil disturbance (SRVC, RLVC, RCVC and RCLC), contributed to a significant decrease in organic C concentration (59, 48, 35 and 47% for the SRVC, RLVC, RCVC and RCLC treatments, respectively) and total N (45, 33, 30 and 44% for the same treatments, respectively) in surface layer (0-20 cm) (Table 3 and Figure 4), being the result of the disruption of the balance between formation and mineralization humus processes (Madeira et al. 1989; Islam and Weil 2000; Saviozzi et al. 2001). In the same treatments, C and N tends to increase in depth, showing significantly higher levels in deeper layer (40-60 cm), which is associated with the migration oforganic matter in the soil profile by the action of tillage. Despite the changes observed in the levels of carbon and nitrogen, Dick et al. (1998) reported that the largest variations in organic matter content occur during the first five years after site preparation, with little variation beyond that period. Available P values (Figure 5A) range from very low (0-25 mg kg -1 ) to low (26-50 mg kg -1 ) (Santos, 1991).
ABSTRACT: Concerns about the negative effectsof agriculture onsoilphysical quality andsoilorganic carbon (SOC) pools have spurred on the adoption of conservation tillage systems in trop- ical regions. This study aimed to evaluate the long-term impacts (16 th year) of conventional (CT), minimum (MT) and no-tillage (NT) practices and different cover crops (sunn hemp and a bean/ millet sequence) onsoilphysicalpropertiesand SOC content of a corn cultivated Ultisol in the northeast of Brazil. Soil bulk density (Bd), soil penetration resistance (SPR), soil aggregation, and total aggregate-associated carbon (C) (4-2 mm) were evaluated. Tillage practices exerted strong control onsoilphysicalpropertiesand total aggregate-C content but were influenced by cover crop species. Minimum tillage presented the lowest Bd, irrespective of cover crop, while NT with bean/millet sequence resulted in the lowest SPR. However, as regards soil aggregation and total aggregate-C, the results indicated that there were no differences between MT and NT, with both systems presenting greater mean weight diameter (MWD) and total aggregate-C content than CT. Total aggregate-C content in the 0.00-0.05 m soil layer in conservation tillage was increased by the adoption of a bean/millet sequence. Increased mechanical disturbance through CT prac- tices was harmful to Bd, soil aggregation and SOC accrual. Overall, more conservative tillage practices and the proper choice of cover crops might yield greater soil quality. Low intensity ofsoil disturbances due to the adoption of MT favors soil aggregation and the accrual of SOC in weakly structured soils through increases in contact between organicand mineral particles while not causing significant destruction ofsoil aggregates.
Castor bean (Ricinus communis L.) is an oilseed crop of outstanding social and economic importance in Brazil and the world. Castor oil is used as a raw material for unique applications in the chemical industry due to the peculiar characteristics of its molecule, which make it the only naturally hydroxylated vegetable oil, as well as due to the composition predominantly containing a single ricinoleic fatty acid, which gives it atypical chemicalproperties (Azevedo & Beltrão, 2007). Castor bean is an euphorbiaceous crop traditionally grown by small producers but commercially exploited due to the high oil content of its seeds. Brazil is one of the three largest producers of castor beans in the world, alternating throughout the history with China and India (Rodrigues et al., 2010).
Within the usable area of each plot, the forage was randomly sampled within a square meter cut at 15 cm ofsoil at intervals of 28 days for the irst four cuts and 30 and 42 days, respectively, for the ifth and sixth cuts. Immediately after sampling, the material was weighed to obtain the green mass yield, followed by homogenization to generate a composite subsample, which was again weighed and dried in a forced air oven at 65°C to constant weight. The result was then transformed into amount of forage yield per hectare.
The field work was carried out in an agricultural area of the municipality of Campos Novos in the midwestern part of the State of Santa Catarina, in the south of Brazil, located at latitude 27 o 22' 59" S, longitude 51 o 15' 33" W and 896 m altitude. The soil is a Hapludox, with clayey texture, deep profile, low slope, and high water storage capacity, where the primary vegetation is that of sub-tropical savannah (Embrapa, 2004). The predominant climate is moist sub-tropical with mild summers, classified as Cfb according to Köppen (Pandolfo et al., 2002).The experiment was carried out in a field, managed with crop rotation and no-tillage for more than 10 years, with the following soilproperties at the 0.00-0.20 m soil depth: pH(H 2 O) of 5.8; 45 g kg -1 ofsoilorganic
28- Suzuki P, Souza V, Holland R, Murata SS, Gomes-Filho Je, Dezan Júnior e, et al. Tissue reaction of the endoReZ in root canal illings short of or beyond an apical foramen like communication. Oral Surg Oral Med Oral Path Oral Rad endod. 2010;109:e94-9. 29- Vasconcelos BC, Bernardes RA, Cruz SM, Duarte MA, Padilha PM, Bernardineli N, et al. evaluation of pH and calcium ion release of new root-end illing materials. Oral Surg Oral Med Oral Pathol Oral Radiol endod. 2009;108:135-9.
The opportunity to supplement common cassava biscuits with a product of higher nutritional value meets consumer expectations. In this work it was studied the effectsof process parameters and flaxseed addition onphysicalpropertiesof expanded snacks. Extrusion process was carried out using a single screw extruder in a factorial central composite rotatable design with four factors: flaxseed flour percentage (0-20%), moisture (12-20%), extrusion temperature (90-130 °C) and screw speed (190-270). The effect of extrusion variables was investigated in terms of expansion index, specific volume, water absorption index, water solubility index, color parameters (L*, a* ,b*) and hardness. The data analysis showed that variable parameters of the extrusion process and flaxseed flour affected physicalpropertiesof puffed snacks. Among the experimental conditions used in the present study, expanded snack products with good physicalproperties can be obtained under the conditions of 10% flaxseed flour, 230 rpm screw speed, temperature of 90 °C and moisture of 12%.
From the point to view of the environmental resolution in force (CETESB, 1990), there is no report in article 21 of parameter or substance that should present the maximum admissible value of the element phosphorus, phosphate or similar for release in a body of water. Excess phosphorus only becomes visible as a pollutant after lixiviation or removal in mud slides to the lakes, causing the eutrophism of these receptor bodies.The average values of phosphate contents in the soil before sowing and after harvest in the treatments are shown in Table 8.
covers was also observed by Quezada-Martin et al. (1992) in the ‘Sprint 440’ cucumber cultivar. This is probably related to water saving due to the polyethylene cover, which enables the plant to complete its cycle in a shorter period. Taber (1993) observed that early harvest increased in melon when soil covers were applied as compared to no covering. Furthermore, the author also observed that the clear polyethylene was more effective in early pro- duction than the black polyethylene. In Brazil, Araújo et al. (1992) found that red or black polyethylene induced earlier production of ‘Vista Alegre’ cucumber when com- pared to the treatment without covering. Furthermore, the authors found that the polyethylene covers also induced earliness of emergence of plants andof the first female flower appearance. On the other hand, Bonanno & Lamont Jr. (1987) found difference in earliness with or without polyethylene only in cooler years. Polyethylene covers (black or clear) did not increase earliness the next year, which was warmer. The authors attributed this fact to the difference in the air temperature, as the soil tem- perature was similar during both years.
The cucumber was purchased in a local market, washed, peeled and cut into slices of approximately 1 cm thick, prior to drying. For the convective drying, a chamber with ventilation was used (Binder WTB), and the operating temperatures were set to 40ºC and 60ºC. In the drying tunnel (Tray Drier UOP-8, Armfield) the temperature was kept at about 60ºC. For these three trials the drying time was 24, 12 and 5 hours, respectively.For the freeze drying, the samples were frozen in a kitchen conventional freezer, and then left in the freeze-drier for 96 hours at a temperature between - 50 ºC and - 54 ºC, and a pressure of 0.7 Pa.
Spatial variation in soil respiration on slopes has been ex- amined in many forest types including Japanese cedar forests (Ohashi et al., 2007), Japanese cypress forests (Mitani et al., 2006), deciduous broadleaf forests (Hanson et al., 1993; Jia et al., 2003) and tropical rain forests (Sotta et al., 2006; Ko- sugi et al., 2007). The slope heights in these studies varied substantially (between 7 and 70 m), but most studies reported lower soil respiration rates in lower parts of the slopes. Jia et al. (2003), Mitani et al. (2006) and Kosugi et al. (2007) noted that the decreased soil respiration rates on lower slopes were caused by higher soil moisture ratios. However, in a study of a weathered granitic area of southern Kyoto Prefecture, Tamai et al. (2005a) linked lower soil respiration rates in ar- eas of elevated topography to increased dryness. This result shows that the relationship between soil respiration andsoil moisture is not unique to any forest and remains unclear.
It was observed that the concentration of N in the plant tissue had increased at the first sampling, though the LWE effect decreased over time (Table 3). Such increases greatly affect pasture quality, as N content is associated with protein concentration and animal performance (SENGER et al., 1996). At the first cutting, the concentration of N in plant tissue showed a linear increase in response to LWE application (Table 3); this was most likely due to the ready availability of N as ammonium in LWE (Table 2). The organic fraction of N in LWE was found in easily mineralized compounds; the C/N relationship is considerably lower than 20/1 (Table 2). Increases in productivity and the concentration of N in plant tissue occurred simultaneously, with a visible change in the leaves in the form of an intense green color. Alvim et al. (1999) and Mazza et al. (2009) also observed a linear response due to increasing rates of nitrogen fertilization.
PHYSICALPROPERTIESOF BIODEGRADABLE FILMS BASED ONCASSAVA STARCH, POLYVINYL ALCOHOL AND MONTMORILLONITE. The objective of this work was to manufacture biodegradable films based oncassava starch, polyvinyl alcohol (PVA) and sodium montmorillonite (Na-MMT), using glycerol as a plasticizer. These films were characterized according to their microstructure, optical, mechanical, and barrier properties. The combination of starch-PVA-MMT resulted in films with a more homogeneous surface than starch films. The introduction of PVA into the starch matrix led to the formation of films with lower water vapor permeability (WVP), higher tensile strength and greater elongation. MMT was exfoliated in the films, resulting in greater stability for different relative humidities, lower WVP, higher resistance and lower flexibility.
The experiment was carried out following a randomized complete block design with four treatments (three replicates), which were designated 100S (a monospecific Sesbania stand), 100E (a monospecific Eucalyptus stand), 50S:50E (a mixed Sesbania and Eucalyptus stand at identical proportions), and DASV (a degraded area with spontaneous vegetation in which Brachiaria mutica (Forsk.) Stapf. prevailed). Each quadrat included 16 plants spaced at 3 × 2 m. During seedling production, the plants were inoculated with arbuscular mycorrhizal fungi (Glomus macrocarpum, Glomus etunicatum, and Entrophospora colombiana) isolated from a clay pit that belonged to another ceramics company, Caco Manga Ltda., located in the Ururaí district, municipality of Campos dos Goytacazes, RJ, Brazil. The isolates, which came from the inoculum bank maintained by the Laboratory ofSoil Studies, Universidade Estadual do Norte Fluminense, were multiplied on Urochloa brizantha grown in a 1:2 (v:v) mixture ofsoiland sand. Inoculation was performed at the time of placing the seeds in the containers with an inoculum of 5 mL of a mixture of rhizospheric soiland fungal spores (approximately 120 spores of G. macrocarpum, 100 of G. etunicatum, and 80 of E. colombiana). In addition to the fungi, the S. virgata seeds were inoculated with 5 × 10 7 cells mL 1 of the specific strain of Rhizobium (BR 5401)