Effect Of Different Rates Research Articles

An Attempt to Reduce the Use of Potassium Fertilization in Jerusalem Artichoke Plants in Clay Soil

A field experiment was carried out at the Experimental Farm of El-Gemmeiza, Agric. Res. Station, El-Gharbeya Governorate, Egypt , during 2019 and 2020 summer seasons,to study the effects of different rates of potassium treatments at 48, 72 and 96 kg/fad. K2O as soil application and K2O concentration treatments at 0,0.5 and 1.0% as foliar application and their interactions on growth, yield and tuber quality of Jerusalem artichoke Fuseau cultivarunder clay soil.The interaction treatments of fertilizing Jerusalem artichoke with K2O at 72 kg /fad. as soil application (SA) and spraying plants with K2O at 1 % four times at 75, 90,105 and 120 days after planting had significantly increased on plant height , number of branches /plant,both fresh and dry weight of shoots/plant, N,P and K contents in shoots and its uptake, average tuber weight , yield / plant and total yield/faddan .While,the interaction treatment between K2O at 96 kg /fad. as soil application and spraying plants with K2O at 1% reflected a significant effect and increased total carbohydrates , inulin,K and dry matter percentages in tuber at harvest time compared with plants received K2O at 48 kg /fad. as SA only in both seasons. Finally, under the same conditions, fertilizing Jerusalem artichoke with K2O at72 kg/fad. as soil application and spraying plants with K2O at 1% reduced the using of potassium fertilizer by 25% and increases in total yield about 9.89 and 6.91 % over fertilizing with 96 kg /fad. K2O only in the 1st and 2nd seasons, respectively.

Effect of different rates of sawdust - piggery compost on soil properties and yield of maize in nutrient depleted soil

Compost is an important source of organic fertilizer that can be used to amend degraded soil to improve soil nutrient and crops yield. This experiment was to evaluate the effect of sawdust – piggery compost on soil properties, growth and yield of maize and it was carried out at the Ambrose Alli University Teaching and Research Farm, Emaudo, Ekpoma, Edo State. The experiment was fitted in a Randomized Complete Block Design (RCBD) with seven treatments and three replicates. The treatments were; control (0), 2, 4, 6, 8, 10 and 12 tonnes of sawdust – piggery compost per hectares (ha-1). Data collected were analysed using ANOVA and LSD was used to separate means. Soil nutrients were below critical levels and the application of compost improved fertility status of the soil. Growth parameters, dry matter yield, cob weight, grain yield and nutrient uptake were determined. It was observed that application of Sawdust – piggery compost significantly (p 0.05) increased the growth of maize compared to control. The application of 8 to 12 tonnes of sawdust – piggery compost significantly (p 0.05) increased the plant height, leaf area and stem girth of maize compared to other treatments. The application of 8 to 12 tonnes per hectares (ha-1) of sawdust – piggery compost significantly (p 0.05) increased the cob weight, grain and dry matter yield of maize compared to other treatments, however, the application of 10 t ha-1 of compost to maize increased grain yield of maize than others rate of applications with the yield value of 4.60 t ha-1. The uptake of nitrogen, phosphorus and potassium were higher with application of 12 tonnes of compost. In conclusion, the application rates of 10 t ha-1 of sawdust – piggery compost per hectare on nutrient depleted soils will improve the growth and yield of maize.

Evaluation of Different Rates of NPS on Growth and Yield Performances of Garlic (Allium sativum L.) in Cheha District, Gurage Zone, Ethiopia

A field experiment was conducted on 2019 growing season to evaluate effects of different rates of nitrogen, phosphorus, and sulfur on growth and yield of garlic under supplemental irrigation. A local variety, Tuma, was used and treated with six rates of NPS (T1 (0 : 0 : 0 kg/ha NPS) (control), T2 (19 : 38 : 7 kg/ha NPS), T3 (28.5 : 57 : 10.5 kg/ha NPS), T4 (47.5 : 76 : 14 kg/ha NPS), T5 (47.5 : 95 : 17.5 kg/ha NPS), and T6 (57 : 114 : 21 kg/ha NPS)). The experiment was laid out in randomized complete block design and replicated three times. Data were collected for days to 50% emergence, plant height, leaf number, leaf length, bulb weight, and total bulb yield. SAS version 9.2 was used to analyze the data. Means were separated using Fisher’s test at 5% level of significance. All parameters were significantly P < 0.05 affected by the rates of NPS. The early days to 50% emergence (16) was recorded from T6 (57 : 114 : 21 kg/ha NPS), whereas the late days to 50% emergence was recorded from the control treatment (T1). Significantly highest leaf length (41.51 cm), leaf number (13.63), plant height (61.19 cm), bulb weight (39.44 g), and total bulb yield (14.91 ton ha−1) were recorded from T6 (57 : 114 : 21 kg/ha NPS). Therefore, from the result of this study, it can be concluded that the maximum total bulb yield of garlic was obtained with the application of 57 : 114 : 21 kg/ha NPS rate.

Maize (Zea mays L.) yield response to the effect of blended fertilizer and varieties under supplemental irrigation at Hadero Zuria Kebele, southern Ethiopia

Maize is one of the staple cereal crops in Ethiopia. However, in southern Ethiopia, the productivity of the crop is very low as compared to the average national productivity, which is mainly attributed to poor soil fertility and the use of low yielding varieties. Hence, a field experiment was conducted at Hadero Zuria kebele, southern Ethiopia under supplemental irrigation to investigate the effects of different rates of blended Nitrogen, Phosphorus, Sulphur, and Boron (NPSB) fertilizer on the performance of maize varieties. Treatments involving three varieties of maize (30G19, BH-546, and BH-547) and six rates of NPSB fertilizer (0, 50, 75, 100, 125, and 150) kg ha−1 were tested in RCBD using a factorial arrangement with three replications. Data on crop Phenological, growth, yield, and yield components were collected. The results showed that the blended NPSB fertilizer rates and varieties of maize affected days to physiological maturity, leaf area, leaf area index, hundred kernels weight (HKW), dry biomass yield (DBY), and grain yield (GY). The highest mean values for HKW, DBY, and GY were obtained from the 150 kg ha−1 NPSB rate. Similarly, the highest values for DBY and GY were obtained from the BH-546 variety. Significant differences (P < 0.05) were obtained on days to tasseling, days to silking, and harvest index (HI) due to the interaction effect of NPSB rates and varieties. As the NPSB rates increased from 0 to 150 kg ha−1, HKW and DBY increased consistently from 29.62 to 36.62 g and 31.41 to 43.70 t ha−,1 respectively. Grain yield showed a highly significant and positive correlation with cob length, leaf number, HI, HKW, and DBY. Also, maximized economic profitability was gained at a rate of 150 kg ha−1 NPSB fertilizer. Thus, from this result, the NPSB rate of 150 kg ha−1 with the hybrid maize variety BH-546 could be better for the study area.

Detoxification difference of cadmium between the application of selenate and selenite in native cadmium-contaminated soil.

Cadmium (Cd) has strong mobility and could cause toxicity to plants, and selenium (Se) can effectively detoxify Cd stress. However, differences in the detoxification effects of different species and dosages of exogenous Se on Cd and its mechanism are still unclear. In this study, a pot experiment was conducted to determine the effects of different rates of selenite and selenate application on radish growth, the uptake and translocation of Cd, and the fractions of Cd transformation in native Cd-contaminated soil. Results indicated that the decrease in radish biomass in selenate treatment was significantly greater than that in selenite treatment at a high Se application rate (2.5 mg·kg-1) (p < 0.05). In contrast to selenite treatments, the application of selenate significantly increased the translocation of Cd from radish roots to shoots (p < 0.05). Cadmium concentration and its bioaccumulation factor in radish decreased gradually with increasing selenite application rates, while these values decreased at low Se rate (1 mg·kg-1) and increased at high Se rate for selenate treatment. Different Se application rates resulted in Cd fractions distributions to change in soil. Therefore, the application of selenite treatment had a greater detoxification effect on Cd in soil than that in selenate treatment, and the double toxic effect was observed between Se and Cd in high selenate treatment (2.5 mg·kg-1). Combined with human health risk asseeement, the application of 2.5 mg·kg-1 selenite could be a good approach for detoxification in native Cd-contaminated soil used in this study.

Impact of manure compost amendments on NH3 volatilization in rice paddy ecosystems during cultivation

Livestock manure has been widely used in agriculture to improve soil productivity and quality. However, intensive application can significantly enhance soil nitrogen (N) availability and facilitate ammonia (NH3) volatilization during rice cultivation. The effects of different rates of manure application on the NH3 volatilization rate, its mechanism, and their relationships have not been comprehensively investigated. In this study, field trials were conducted to investigate NH3 volatilization in rice paddy soils amended with different livestock manure, cattle manure (CM), and swine manure (SM), at a rate of 0 (NPK), 10, 20, and 40 Mg ha−1 during cultivation. Moreover, the soil physicochemical and biological properties and rice N uptake were investigated. Ultra-fine particulate matter (PM2.5) was measured quantitatively and qualitatively. Manure application significantly increased NH3 emissions compared to the control. Much higher volatilization rates were observed in the SM soils than in the CM soils, even when the same amount of N was applied. This is mainly related to the higher labile NH4+ concentration and urease activity in SM soils. With increasing application levels, NH3 emission rates proportionally increased in the SM, but there was no significant difference in the CM. Livestock manure application significantly increased NH3 volatilization, particularly during the initial manure application and additional fertilization stages during rice cultivation. The results showed that the application of livestock manure significantly increased NH3 volatilization. Moreover, the biochemical properties of manure composts, including labile N and urease activity, mainly affected NH3 dynamics in rice paddies during cultivation rather than their type. Irrespective of manure application, PM2.5, did not show a significant difference at the initial stage of cultivation. NH3 volatilization was not significantly correlated with the formation of PM2.5. It is necessary to develop effective strategies for mitigating NH3 volatilization and maintaining soil quality without decreasing rice productivity in paddy ecosystems.

The Effects of Different Rates of Chicken Manure and Harvest Intervals on the Bioactive Compounds of Bitter Leaf (Vernonia amygdalina Del.)

Bitter leaf (Vernonia amygdalina Del.) is a valuable functional vegetable and traditional medicinal plant in many tropical countries including Indonesia. Bitter leaf is commonly used to remedy hypertension and diabetes among Indonesian people. The leaf extract comprises bioactive compounds such as sesquiterpene lactones, steroid glycosides, and flavonoids. Despite its growing market demand, there is insufficient data on agronomic practice in order to obtain optimum yield with high bioactive compounds. The experimental design used was a randomized complete block design with two factors namely chicken manure rates (0, 2.5, 5, and 7.5 kg per plant) and harvest intervals (2 and 3 months). There was a significant difference in fresh and dry weights of leaves, chlorophyll a and b, carotenoids, nitrogen concentration, anthocyanins, and flavonoids among different manure treatment. The highest concentration and production of bioactive compounds on the bitter leaf was found on the highest treatment of 7.5 kg chicken manure per plant. The harvest interval of three months significantly increased fresh and dry weights of leaves, concentration of anthocyanins, phosphorus, and potassium, uptake of phosphorus and potassium, and production of anthocyanins and flavonoids. Cultivation using chicken manure with frequent period of pruning can enhance the production of biomass as well as secondary metabolites in bitter leaf.

ВМІСТ ФОТОСИНТЕТИЧНИХ ПІГМЕНТІВ У ЛИСТКАХ ГРЕЧКИ ЗА ДІЇ БІОЛОГІЧНИХ ПРЕПАРАТІВ

The article presents the results of a field experiment to study the effects of different rates of the microbial preparation Diazobacterin under different methods of using the plant growth regulator Radostim (seed treatment before sowing and spraying crops) on the content of chlorophyll a and b in buckwheat leaves of Yelena variety, their sum and carotenoids. Determination of chlorophyll a and b, their sum and carotenoids was performed in selected samples of buckwheat leaves in the field conditions, in the phases of stem branching and the beginning of flowering according to the method described by V.F. Gavrylenko and T.V. Zhyhalova using a spectrophotometer. The pigment concentration was calculated from Holm-Wettstein's equations for 100 % acetone. It was found that the content of photosynthetic pigments in buckwheat leaves is conditioned by the weather, rates and methods of application of the studied microbial preparations and phases of plant development. In particular, the analysis of chlorophyll and carotenoid content in the early flowering phase of buckwheat plants showed a significant increase compared to the phase of stem branching, which may be due to increased physiological and biochemical processes in plants, against the background of improving mineral nutrition, growth and plant development. Thus, with the multiple use of the microbial preparation Diazobacterin in the rates of 150, 175 and 200 ml and the stimulator of plant growth Radostim in the rate of 250 ml / t for seed treatment before sowing, the content of chlorophylls a and b, their sum and carotenoids with increasing application of Diazobacterin increased and the excess relative to control ranged within: 29–31 % for chlorophyll a; 10–11 % for chlorophyll b; 24–26 % for their sum and 23–24 % for carotenoids. At the same time, with a complex application for pre-sowing seed treatment of a mixture of the microbial preparation Diazobacterin in the rate of 200 ml per hectare of seeds with the stimulator of plant growth Radostym in the rate of 250 ml / t followed by spraying on this background crops the stimulator of plant growth Radostim in the rate of 50 ml / ha buckwheat leaves form the highest content of chlorophyll a in comparison with the control (40 %); chlorophyll b (15 %); the sum of chlorophyll a + b (33 %) and carotenoids (29 %). These data indicate the creation of more favorable conditions for physiological and biochemical processes in plants, including photosynthesis, with the direct positive effect of which, functionally active pigment complex of the leaf apparatus of buckwheat is formed.

Response of sweet pepper plants to foliar application of compost tea and dry yeast under soilless conditions

BackgroundSweet pepper is considered one of the most important vegetable crops cultivated for local consumption and exportation. Under greenhouse conditions, the effects of different rates of yeast and compost tea on vegetative growth, leaves mineral content, fruit yield and quality were studied for two consecutive years 2018/2019 and 2019/2020 under soilless conditions. Nine treatments of compost tea (CT) and or dry yeast (DY) were applied using control (sprayed with distilled water); CT (10L/fed.); CT (20 L/fed.); DY (3 g/L); DY (6 g/L); CT (10L/fed.) + DY (3 g/L); CT (20L/fed.) + DY (3 g/L); CT (10L/fed.) + DY (6 g/L) and CT (20L/fed.) + DY (6 g/L).ResultsResults showed that the mixture of compost tea and dry yeast at a rate of 20 L./fed. plus 6 g/L, respectively, had significantly increased vegetative growth, fruit physical quality (length, diameter and fresh weight), total yield, leaves mineral content (N, P and K) and fruit nutritional value content (calcium and vitamin C). The maximum return or profit comes from the CT (20 L/fed) + DY (6 g/L) followed by CT (20 L/fed) + DY (3 g/L.)ConclusionIt is clear that all treatments enhanced the yield and the fruit physical parameters of the studied plants as well as all treatments are economically feasible including the control treatment. However, looking at the Revenue/Cost ratio (R/C), one can find that the maximum net revenue comes from the mixture of CT (20 L/fed) plus DY (6 g/L) with a net revenue about 192.72 L.E./m2 and R/C ratio of 1.90, followed by CT (20 L/fed) + DY (3 g/L.).

Effects of chloropicrin fumigation combined with biochar on soil bacterial and fungal communities and Fusarium oxysporum

Chloropicrin (CP) can cause long-term damage to beneficial microbes which reduces soil health. Biochar (BC) can mitigate against the effects of CP by reducing the time for beneficial microbes to recover after CP fumigation. In this study, we used Real-Time Quantitative PCR to determine the effects of different rates of BC added to CP-fumigated soil on the speed of recovery of bacteria and fungi population and on changes to gene copy number of the target pathogen Fusarium oxysporum. And then we compared the structure and composition of the beneficial microbial community in the different treatments soil by using High throughput Illumina sequencing. As the results shown, adding 1 or 3% BC after CP fumigation accelerated the recovery of bacterial and fungal populations without increasing F. oxysporum abundance. BC also promoted the recovery of beneficial bacteria Rokubacteria and Latescibacteria damaged by CP. And these two bacteria may be related to the immunity of soil to F. oxysporum. In CP-fumigated soil, BC improved the disease resistance of the soil by increasing beneficial microbes, such as Steroidobacter, Sphingomonas, Purpureocillium and Mortierella. This combination of CP and BC is a new concept that could encourages the development of a healthy and sustainable soil ecosystems while controlling plant pathogens.

Ethephon as a potential tool to manage alternate bearing of ‘Fuji’ apple trees

The objective of this study was to investigate the effect of different rates of ethephon on return bloom and yield, and fruit quality of ‘Fuji’ apple trees. The experiment was performed during the 2014/2015 and 2015/2016 growing seasons. Eighteen-year-old Fuji Standard apple trees grafted on M.9 were sprayed with different rates of ethephon (300 mg L-1, 400 mg L-1, and 500 mg L-1) 30 days after full bloom (DAFB) and compared to an unsprayed control. Yield components (number of fruit per tree, yield, fruit weight, and estimated yield) and fruit quality attributes (fruit firmness, total soluble solids and starch-iodine index) were evaluated in both seasons. Return bloom (percentage of flowering spurs and 1-year-shoots) was assessed only the year following the application. Our results show that ethephon increases return bloom and yield of ‘Fuji Standard’ apple trees, without affecting fruit quality attributes.

Growth, yield, and postharvest quality of cabbage (Brassica oleracea L.) in response to different levels of nitrogen fertilizer

In the Philippines, vegetable farmers generally apply excessive amounts of fertilizer to maximize yield while not understanding the cost impacts and environmental effects. This study aimed to evaluate the effects of different rates of nitrogen fertilizer on the productivity of two cabbage cultivars. The experiment was conducted as a factorial using a randomized complete block design in two growing seasons. The two factors included level of nitrogen (21, 141, 191, 241, 291, 341 and 391 kg N ha-1) and cultivar ('Resist Crown' and 'KEX-734') with each treatment combination replicated four times. The study showed that application of 291 kg N ha-1 resulted in the highest dry matter, largest heads (polar and equatorial) and highest average yield (35.49 t ha-1) in the two growing seasons. At 391 kg N ha-1, cabbage yielded the highest number of leaves and leaf count increased concomitantly with increasing N application rate. Results further showed that N application at the highest rate (391 kg N ha-1) resulted in the highest postharvest weight loss (33.7%) and shrivelling of cabbage heads. The cultivar 'Resist Crown' produced a greater number of leaves, largest polar head size and consequently highest mean yield (25.7 t ha-1) than cultivar 'KEX-734' in both cropping seasons. The results indicate that an application rate of about 291 kg N ha-1 is recommended for cabbage production since it increases yield through enhancing the size and weight of the cabbage head. 'Resist Crown' was a better cultivar than 'KEX734' having greater yield and postharvest quality. © 2021 International Society for Horticultural Science. All rights reserved.

The Effect of Different Rate of Biofertilizer on the Growth Performance and Yield of Rice

Rice (Oryza sativa L.) is an important cereal in the world and can be grown in different habitats such as lowland, irrigated and upland rice. In order to study the effects of biofertilizer on the growth performance and yield of rice, the experiment was carried out using Complete Randomized Design (CRD) based on 5 treatments with 5 replications. The control treatment (T0) was 100% of NPK fertilizer, treatment 1 (T1) was 30% biofertilizer and 70% NPK fertilizer, treatment 2 (T2) was 50% biofertilizer and 50% NPK fertilizer, treatment 3 (T3) was 70% biofertilizer and 30% NPK and treatment 4 (T4) was 100% biofertilizer. The rice variety used was MR 220 and different doses of biofertilizer were applied 4 times. Each of the application was mixed with inorganic fertilizer NPK at a recommended rate. The parameters used in this study were number of leaves, number of tillers, number of panicles, height of rice, 1000-grain weight and fresh weight. In this experiment, treatment 2 (50% biofertilizer and 50% NPK) showed positive result for all parameters and has significant difference between the treatments. Treatment 3 (70% biofertilizer and 30% NPK) showed the lowest means for most of the parameters. Thus, from this study, the combination of 50% biofertilizer with 50% chemical fertilizer is proved to boost a better growth and yield of rice.

Cotton root growth response to mepiquat chloride application in early reproductive stages are cultivar dependent

AbstractMepiquat chloride (MC) is essential to reduce shoot growth and improve cotton (Gossypium hirsutum L. var. latifolium Hutch) harvest index, but the effect of high rates on cotton root growth is not known yet. The objective of this study was to evaluate the effect of different rates of MC application on root and shoot growth of different cotton cultivars. Two studies were conducted in a greenhouse to (a) characterize the stage of greatest susceptibility to high rates of MC and (b) evaluate the response to MC on root growth of cultivars of different maturity cycles (FM 906GLT, early; TMG 44B2RF, mid‐early; TMG 81WS, late; and FM 985GLTP, late). Regardless of the cultivar, spraying of MC in the early reproductive stage (B3) reduced root length. These reductions began approximately 2 wk after spraying. But spraying MC in the late reproductive stage (F1) can increase root length. Application of up to 30 g ha−1 of MC hindered shoot growth for 2 wk, but applications of 60 g ha−1 hindered shoot growth for 3 wk. We recommend a maximum application of 30 g ha−1 of MC in the first application to reduce root growth damage and balance biomass production.

Response of Two Purple basil (Ocimum basilicum L.) Cultivars Grown Under Field Conditions to Different Rates of NPK Foliar Fertilization

A field experiment has been used two purple cultivars of basil (Ocimum basilicum L.) during summer of 2019 at Al-Diwaniyah Station for Crop Cultivation and Development, Al-Diwaniyah city, Iraq, to study the effect of different rates of NPK on some vegetative characters and oil yield. The treatments comprised different rates (0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 g.L−1) of NPK foliar fertilization which were applied after 50 DAP. Obtained results revealed that NPK had significant effect on all parameters tested in both cultivars. Red Rubin cultivar showed a linear relationship between all parameters tested and NPK rates. However, only one parameter; plant height, showed this relationship in Dark Opal cultivar at which, all other four parameter showed polynomial relationship. The maximum values for the parameters were obtained at the 3.0 g.L−1 NPK treatment for Red Rubin cultivar and at 1.5-2.5 g.L−1 NPK treatments in most parameters for Dark Opal. It can be concluded that NPK application had a pronounced beneficial effect on basil plant.

EFFECT OF ADDING BIOCHAR AND DIFFERENT RATES OF CHEMICAL FERTILIZATION ON GROWTH AND YIELD OF GLOBE ARTICHOKE PLANTS GROWN IN SANDY SOIL

A field experiment was carried out during two successive winter seasons of 2017/2018 and 2018/2019 at the Experimental Farm of El-Kassasin Horticultural Research Station, Ismailia Governorate, Egypt, to study the effect of different rates of mineral NPK ( 100, 75, 50 and 25 % of the recommended rates) and biochar (0, 1, 2 and 4 m3/fad.) on growth, yield and head quality of globe artichoke plants grown in sandy soil. Results showed that , the interaction between fertilizing globe artichoke plants with NPK at 100 % of recommended rates (RR) and treating with biochar at 4 m3/fed, significantly increased plant height , leaf fresh weight and offshootsnumber / plant, highest number ofearly heads/ plant , number of total heads/ plant , total yield / plant , total yield /fed. and total sugars (%) in receptacle in both seasons. While, the interaction between fertilizing globe artichoke plants with NP K at 75 % of RR and treating with biochar at 4 m3/fed. significantly enhanced leaf dry weight and all flower head quality such as head fresh weight, head diameter, receptacle fresh weight, receptacle diameter and receptacle thickness, with no significant differences between the interaction treatment between fertilizing with NP K at 100 % RR and treating with biochar at 4 m3/fed. in both seasons.However, reducing sugars and inulin (%) significantly enhanced with the interaction treatments between NPK at 100 or 75% of RR and treating with biochar at 4 or 2m3/fed. in both seasons . On the other hand, the lowest values of all plant growth parameter, yield and its components, head quality and chemical constituents of receptacles were obtained from the plants which received 25 % of the recommended rate of NPK in without biochar both seasons. Conclusively, it could be concluded that, fertilizing globe artichoke plant with NPK at 100% from recommended rate which equal 120 kg N, 62.0 Kg P2O5 and 120 kg K2O and treated with 4 m3/fed. was the best treatment for recorded the highest values of yield characters, and head quality under the similar conditions compared to the other studied treatments.

Use of the imazapic herbicide applied alone or tank mix with imazapyr as growth regulator of lawns

Successive mowing are the major maintenance costs of lawns. Thus, both the expenditure with mowing and the visual and physiological aspect of the lawn have led to the search for alternatives to mechanical management. Thus, this work aimed to study the effects of different rates of imazapic herbicide applied alone or combined with imazapyr as a growth regulator of Bahiagrass (Paspalum notatum) and St. Augustine grass (Stenotaphrum secundatum). The experimental design was a randomized block with four replicates, and the treatments consisted of six rates of imazapic herbicide (35; 70; 105; 140; 175 and 210 g a.i. ha-1) for both species, three rates of imazapic + imazapyr in tank mix (15.57 + 5.25; 23.625 + 7.875; 32.5 + 10.5 g a.i. ha-1) for Bahiagrass and four rates of imazapic + imazapyr mixture (7.875 + 2.625; 15.57 + 5.25; 23.625 + 7.875; 32.5 + 10.5 g a.i. ha-1) for St. Augustine grass. The effect of the treatments was evaluated by observing visible injury symptoms, canopy height, height and number of inflorescences and total dry matter of clippings. Applications of imazapic alone or combined with imazapyr were effective in reducing plant height, number and height of inflorescences and total amount of dry matter of clippings produced by Bahiagrass plants. Imazapic provided satisfactory control of St. Augustine growth, but its utilization caused an increase in the number of inflorescences present in the lawns.

Simulation of hydraulic fracturing and Darcy fluid flow in a porous medium using a coupled Discrete Element Method with fluid flow

Studying fluid penetration of the rock matrix during fracture propagation is one of the most difficult technical challenges of hydraulic fracture engineering. To deal with this issue, a coupled hydraulic-mechanical model was performed to simulate fracture propagation during hydraulic fracturing. For this purpose, a new discrete elements approach with a force-displacement law was used for simulating the fracturing process in a flow-coupled Discrete Element Method (DEM). A series of cases was simulated to evaluate the effect of different rates of injection and permeability. Good agreement was obtained between the numerical results of this study and the reported experimental results. The results of hydraulic fracture modeling indicated that a low fluid viscosity led to wider fluid penetration and simultaneous occurrence of failure phenomenon and penetration. In the case of high viscosity, the fracture is propagated beyond the fluid penetration zone, and higher fluid pressure for fracture creation was needed than was the case for a low viscosity fluid. The results of the simulations with different permeability and low viscosity of fluid revealed that when the permeability was high, the fluid penetration was faster relative to the case with low permeability. The growth pattern of fracture in low permeability is straight and branching, but in the case of high permeability, the fracture pathway was straight and thick. The pressurization rate affected the number of cracks and the geometry of the fracture in the hydraulic fracturing model. Finally, an increase in pressurization rate resulted in an increase in the number of tensile cracks.

Modeling habitat suitability and management options for maintaining round whitefish (Prosopium cylindraceum) in Adirondack ponds

Habitat loss, acid precipitation, and non-native species have drastically reduced the number of Adirondack waterbodies occupied by round whitefish (Prosopium cylindraceum). The goal of this study was to (1) increase the probability of reintroduction success by modeling the suitability of ponds for reintroduction and (2) better understand the effects of different rates of pond reclamation. We created a species distribution model that identified 70 waterbodies that were physically similar to occupied ponds. The most influential variables for describing round whitefish habitat included trophic, temperature, and alkalinity classes; waterbody maximum depth; maximum air temperature; and surrounding soil texture and impervious surface. Next, we simulated population dynamics under a variety of treatment scenarios and compared the probability of complete extirpation using a modified Markov model. Under almost all management strategies and under pressure from non-native competitors such as those observed in the past 30 years, the number of occupied ponds will decline over the next 100 years. Restoring one pond every 3 years, however, would result in a 99% chance of round whitefish persistence after 100 years.

Effect of Organic Manures Application on Soil Physicochemical Properties of Coarse-textured Ultisol and Okra Productivity in Nsukka, Southeastern Nigeria

Background: The greenhouse and field studies were carried out to assess the effect of different rates of poultry manure (PM), pig slurry (PS) and the recommended NPK fertilizer on some soil physico-chemical properties and okra yield of coarse-textured Ultisols in Nsukka, southeastern Nigeria. Methods: The PM and PS were applied at three different rates (10, 20 and 40 t ha-1) as well as no amendment as control and the recommended NPK fertilizer (300 kg/ha) and replicated five times. Soil and agronomic data collected were analyzed for variance (ANOVA) using Genstat 4.0.Result: The PM and PS significantly (p less than 0.05) improved soil pH, soil organic matter, available phosphorous, total nitrogen, aggregate stability, mean weight diameter, bulk density, porosity and saturated hydraulic conductivity in greenhouse and field studies. Significant improvement in CEC was obtained in the field study. The PM and PS significantly (p less than 0.05) improved agronomic parameters e.g. plant height, number of leaves, biomass weight and yield of okra than the control. Poultry manure showed its superiority over other amendments in improving soil and agronomic properties. The study recommended 20 t ha-1 of PM and 40 t ha-1 of PS for sustainable soil and optimum productivity of okra in Nsukka, southeastern Nigeria.