Optimum Fertilizer Rate Research Articles

Interaction of Nitrogen and Phosphorus on Wheat Yield, N Use Efficiency and Soil Nitrate Nitrogen Distribution in the North China Plain

To establish the optimal fertilization rate to maintain high wheat yield and low environmental risk in the North China Plain, a two-year field experiment (2016–2018) was conducted with six combinations of two N rates (N0; N1: 240 kg ha−1) and three P rates (P0; P1: 150 kg ha−1; P2: 240 kg ha−1) to investigate the effects of these regimes on wheat grain yield, N assimilatory enzyme activity (nitrate reductase, NR and glutamine synthetase, GS), N use efficiency (NUE) and soil nitrate nitrogen distribution. Results showed that N application increased grain yield and grain protein concentration (GPC) significantly, in association with increased residual soil nitrate in both growing seasons, across the three P application rates. Only P application had no effect on these parameters. Significant interactions of N and P fertilizer were found on most of the tested parameters. Highest grain yield, GPC and NUE, and the lowest residual soil nitrate were observed under the treatment of N1P1. N accumulation in plant was highly correlated with grain yield and NUE, and N assimilatory enzyme activity at flowering was highly correlated with grain yield and GPC, which contributed to achieving high yield and NUE simultaneously. Regression analysis showed that the response of grain yield, NUE and residual soil nitrate to P rates fitted quadratic model, in which the maximum values of grain yield, NUE and the lowest residual soil nitrate were obtained at the extent of P rate 140 ~ 150 kg P ha−1. Hence, we recommended fertilizer rate of N 240 kg ha−1 and P 150 kg ha−1 as the optimal nitrogen-phosphorus regime in the North China Plain, which can maintain higher crop yield while lower environmental risk.

Relationship of frozen-thawed semen quality with the fertility rate after being distributed in the Brahman Cross Breeding Program.

Background and Aim:Various factors can reduce the quality of semen used for artificial insemination and have an impact on fertility decline, such as poor handling during frozen semen distribution. This study was aimed at assessing the quality of frozen-thawed semen after distribution in the field and its importance in maintaining fertility.Materials and Methods:The Brahman Cross (BX) breeding program of PT Lembu Jantan Perkasa, Indonesia, was used. This program was preferred due to its adherence to guidelines that limit the effects of extraneous factors that may affect semen quality. Frozen-thawed semen samples from eight bulls with the same production code were analyzed and compared between the production site (artificial insemination [AI] center) and the field (BX breeding program). Total and progressive motility (PM) of sperm were determined using computer-assisted semen analysis. Plasma membrane integrity (PMI) was assessed using hypoosmotic swelling test, sperm viability using Eosin-Nigrosin staining, acrosome integrity using trypan blue-Giemsa staining, morphological abnormalities using William staining, and DNA fragmentation using toluidine blue staining. The fertility rate was determined using the conception rate (%) derived from AI data based on 502 AI services and 478 cows in the BX breeding program. A t-test was used to compare the quality of frozen-thawed semen before and after distribution. The relationship between the qualities of frozen semen after distribution in the field with fertility was analyzed using Pearson correlation.Results:There was no significant difference (p>0.05) in the quality of frozen-thawed semen (sperm motility, PMI, viability, acrosome integrity, abnormalities, and DNA fragmentation) between the production site (AI center) and after distribution in the field (BX breeding program). The semen met the minimum standards for AI programs. Total motility (r=0.986), PM (r=0.961), sperm viability (r=0.971), PMI (r=0.986), and acrosome integrity (r=0.992) were all positively correlated (p<0.05) with fertility rate; while sperm abnormalities (r=−0.996) and sperm DNA fragmentation (r=0.975) were negatively correlated (p<0.05) with fertility rate.Conclusion:The study showed that to achieve the maximal and optimal fertility rate in bulls in an AI program, the overall quality of frozen-thawed semen in all aspects is critical. This can be achieved if the handling during distribution and storage, as well as the various factors that may affect the quality of semen in the field, can be controlled properly.

Integrated application of compound NPS fertilizer and farmyard manure for economical production of irrigated potato (Solanum tuberosum L.) in highlands of Ethiopia

Application of organic and inorganic fertilizers is essential for sustainable production of crops including potato. This study was therefore initiated to identify the optimum rate of farmyard manure (FYM) and blended compound NPS fertilizer for profitable production of potato in Koga Irrigation Scheme, Northwestern highlands of Ethiopia. Four rates of FYM (0, 4.5, 9, and 13.5 t ha−1) and NPS fertilizer (0, 81.7, 163.4, and 245.1 kg ha−1) were laid down in Randomized Complete Block Design with three replications. The results revealed that FYM and blended NPS fertilizer as well as their combination influenced most of the tested growth and yield parameters of potato including plant height, main stem number, and tuber weight. Application of 245.1 kg ha−1 NPS combined with 13.5 t ha−1 FYM recorded the highest marketable and total tuber yields of 43.52 and 47.04 t ha−1, respectively. Although, the highest marginal rate of return was obtained from plants supplied with the combination of 4.5 t ha−1 FYM and 163.4 kg ha−1 NPS fertilizer, combined application of 245.1 kg ha−1 NPS and 13.5 t ha−1 FYM is recommended for economical production of potato in the study area as it recorded the highest net benefit with acceptable marginal rate of return.

Profitability of using nitrogen fertilizer or inoculating soybean seed

AbstractApplying supplemental fertilizer N or inoculating soybean [Glycine max (L.) Merr.] seed with Bradyrhizobium japonicum led to mixed yield responses. We assessed the profitability of seed inoculation, fertilizing with N, or both, across different planting dates using maturity group (MG) IV and MG V soybean cultivars under irrigated conditions. Planting dates ranged from late May to late June at Fayetteville, AR, and Pine Tree, AR, from 2017 to 2019. Urea fertilizer was applied at R2 at 0 or 56 kg N ha−1 using inoculated soybean. Similarly, non‐inoculated treatments ranged from 0, 28, 56, 112, to 168 kg N ha−1. Although fertilizer did increase yield, the response varied by planting date, was small, and only significant at p = .141 and .171 for linear and non‐linear effects of N, respectively. Seed inoculation had a small negative impact (89 kg ha−1) on yield (p = .0157). Using historical prices over the last 10 yr, optimal fertilizer rates ranged from 3.6 to 6.6 kg N ha−1 with an attendant average yield increase of 32 kg ha−1 for early planting and from 2.6 to 4.1 kg N ha−1 for late planting with an average yield gain of 24 kg ha−1. Regardless of timing of planting, the added yield less attendant fertilizer cost resulted in an average net gain of US$7.39 and $6.00 ha−1, for early and late planting, respectively. That net gain was insufficient to cover additional custom fertilizer application charges of $17.30 ha−1. Hence, inoculation and fertilizer N are not recommended.

Drip fertigation regimes for winter wheat in the North China Plain

To establish the optimum fertilization rate and propose an appropriate drip fertigation regime for winter wheat in the North China Plain (NCP), a three-year field experiment was conducted to evaluate the effects of drip fertigation levels on soil available nutrients, winter wheat growth, grain yield, partial factor productivity (PFP), and irrigation water use efficiency (IWUE) during 2014-2017. The experiment investigated five fertilization rates: 20%, 45%, 70%, 95%, and 120% of the local recommended fertilizer dose (336 kg/ha N and 169 kg/ha P2O5) for high grain yield. The results showed that with the increase of fertilization rates, the concentrations of the soil available nitrogen (N) and phosphorus (P) in the 0–140 cm layer increased, and especially the N in deep layer (100–140 cm) and the P in surface layer (0–20 cm) increased evidently by 0.64 and 0.06 mg/kg with each unit increased of fertilization rate, respectively. Compared with the initial available nutrient concentrations, the fertilization rate of 45%–70% could basically maintain the balance of soil available N, and the fertilization rate of 70% provided a good balance for soil available P. Different fertilization rates had significant effects on winter wheat plant height (H), maximum leaf area index (LAI), dry matter (DM), grain yield, PFP, and IWUE. With each unit of increase in the fertilization rate, the winter wheat yield increased rapidly by 0.61% in the fertilization rate from 20%–70% and slowly by 0.32% in the fertilization rate from 70%–120%. The PFP decreased according to a power function with the increasing fertilization rate. Compared to the average grain yield and PFP under the local surface irrigation regime, drip fertigation of 70% of the local recommended fertilizer dose resulted in a yield increase of 4.0% and a PFP increase of 48.5%. To achieve a relatively high grain yield, high fertilization use efficiency, and minimize risk of environment pollution, a reduction in the fertilization rate to 70% of the local recommended fertilization dose (235 kg/ha N and 118 kg/ha P2O5) was suggested for winter wheat production under drip fertigation in the NCP.

Estimation of NPK requirements for rice production in diverse Chinese environments under optimal fertilization rates

Estimating crop nutrient requirements is essential for informing decisions of optimal nutrient management, but nutrient requirements often vary among climates and soil conditions. We assessed the nitrogen (N), phosphorus (P), and potassium (K) requirements of irrigated rice (Oryza sativa L.) in regions throughout China with different climates and soil chemical properties based on 3,896 measurements. We defined nutrient requirements as the aboveground uptake of N, P, and K required to produce 1 Mg of grain. The N and K requirements increased with increasing daily average temperature, solar radiation, N and K fertilizer rate, soil total N, Exchanged-K and organic matter content, total rainfall and potential evapotranspiration (ET) during the rice growing season and decreased with increasing growth duration, and harvest index (HI). In contrast, the P requirement mainly decreased with daily average temperature and solar radiation, increased with P fertilizer rate, soil Olsen-P. The estimated N, P, and K requirements of rice were 15.3, 6.0, and 19.9 kg Mg–1 grain in northern China and 21.0, 4.4, and 22.1 kg Mg–1 grain in southern China, respectively. The lower N and K requirements in northern China were attributed to lower nutrient concentrations and lower daily average temperature, solar radiation, total rainfall, ET, soil total N, and exchanged-K. The higher P requirement in northern China was mainly attributed to higher grain and straw P concentrations, which could be explained by the lower daily average temperature, solar radiation. Our results update the estimates of rice nutrient requirements based on direct field measurements, and these estimates help address disparities in Chinese nutrient budgets, develop and evaluate models and improve regional nutrient management to support research and policy.

Different Compost Materials Used as Source of Organic Matter in Production of Chili Pepper

Compost has been commonly used as the primary organic matter in organic plant production, especially in vegetable production. Different sources of compost materials give different medium structures and chemical characteristics. The objectives of this research were: 1) to evaluate the response of growth and yield of chili pepper to a rate of compost and source of animal waste which were used as compost; 2) to determine the optimum rate of fertilizer for the highest growth and yield of chili pepper. The research was carried out from November 2015 until March 2016. Compost material treatments consisted of cow dung, empty palm oil bunches, and mixed of vegetable residue and weeds. The compost rate treatments consisted of 0 ton ha-1, 10 ton ha-1, 20 ton ha-1, and 30 ton ha-1. No interaction between the two treatments was found to influence plant growth and yield variables. The type of compost materials affected plant height of 5, 6, and7 weeks after transplanting. Cow dung as a source of compost showed the best effect in increasing chili plant height. Plant height, the number of plant dichotomous, and plant canopy responded linearly to the increase of the compost rate. The usage of compost at 20 ton ha-1 and 30 ha-1 resulted in higher fruit length, the number of fruit, and fruit weight per plant. Keywords: chili pepper, compost, organic, growth, yield

Allometric approach to crop nutrition and implications for crop diagnosis and phenotyping. A review

Historically, the agronomic focus of crop mineral nutrition has yielded responses to individual elements (N, P, K…) to determine the economically optimum fertilization rates. This “prognostic” approach required several parameters for crops, climates, and soils that are often estimated with large uncertainty leading to over-fertilization and environmental problems in some systems (e.g., maize in China), and under-fertilization and soil mining in other systems (e.g., wheat in Australia). In this review, an alternative approach is developed for reducing the uncertainty intrinsically linked to this prognostic approach. Our approach is based on four propositions: (1) the evidence of an allometry between the metabolic shoot mass (scaling with leaf area) and the structural shoot mass (supporting and vascular tissues) within plants that allows the formulation of critical N dilution curves and the determination of the Nitrogen Nutrition Index (NNI) for estimating the N nutrition status of field crops; (2) the co-regulation of crop N uptake dynamics by both soil N supply and crop N demand in relation with its growth capacity that allows a better, more generalizable estimation of timing and rate of fertilizer; (3) a better understanding of the effects of genotype–environment–management interactions on N use efficiency in cropping systems reducing then drastically uncertainties linked to the classical prognostic approach for N fertilization; (4) as P and K also relate allometrically with biomass, P and K concentrations can be directly related to N concentration for the formulation of a multi-element diagnosis of crop nutrition. Here, we develop the theoretical background supporting these four propositions and outline implications for both fertilization management and crop phenotyping.

Optimum rate of NPS fertilizer for economical production of irrigated onion (Allium cepa L) in Dembyia District of Amhara Region, Ethiopia

Onion is one of the most important vegetable crops grown under irrigation in Amhara Region. Application of fertilizer is an important input to increase yields of vegetables including onion where its rate mostly depends on the fertility status of the particular soil. The present study was initiated with the objective to identify the optimum rate of the newly introduced NPS fertilizer for maximum bulb yield of onion under irrigated smallholder farming system. The study was conducted in Dembyia District during the 2014/2015 irrigation season. Twelve NPS fertilizer rates were laid down on Randomized Complete Block Design (RCBD) with three replications to identify the optimum rates of NPS where maximum yield of Adama Red onion variety can be obtained. The results of the experiment revealed that most of the growth and yield parameters of onion were significantly affected by NPS fertilizer. The longest plant height (60.1 cm) was recorded when N:P2O5:S was applied at the rate of 73.5:92:16.95 kg ha-1, respectively. The longest (51.1cm) and widest (1.44 cm) onion leaves were recorded on plants where N:P2O5:S was applied with 136.5:119.6:22 kg ha-1. Onion plants supplied with 105:119.6:22 kg ha-1 N:P2O5:S fertilizer rate gave the highest mean bulb weight (198.8 g), marketable yield (20.8 ha-1) and total bulb yield (21.4 t ha-1). Similarly, onion plants supplied with 105:119.6:22 kg ha-1 N:P2O5:S fertilizer rate recorded the highest marginal rate of return followed by those onion plants supplied with 105: 92:16.95 kg ha-1. Onion plants which were not supplied with NPS fertilizer showed generally lower growth and yield parameters. Application of NPS fertilizer at the rate of 105:119.6:22: kg ha-1 N:P2O5:S can be recommended for economical production of onion in the study area.

The optimal population size under pollution and migration externalities: a spatial control approach

We analyze the implications of pollution and migration externalities on the optimal population dynamics in a spatial setting. We focus on a framework in which pollution affects the mortality rate and decreases utility, while migration occurs within the spatial economy. Agents optimally determine their fertility rate which, along with pollution-induced mortality and spatial migration, determines the net population growth rate. This setting implies that human population follows an endogenous logistic-type dynamics where fertility choices determine what the optimal limit of human population will be. We compare the decentralized and the centralized outcomes showing that such fertility decisions generally differ, quantifying the extent to which pollution and migration induced externalities matter in determining the difference between the two outcomes. We show that, due to the effects of pollution on utility and mortality, both the optimal fertility rate and the population size are smallest in the centralized economy but migration effects change not only the size of these differences but also their direction, suggesting that the spatial channel is an important mechanism to account for in the process of policymaking.

Effect of Different Level of Nitrogen Fertilizer on Growth, Yield and Yield Component of Tomato (&amp;lt;i&amp;gt;Lycopersicon Esculentum Mill&amp;lt;/i&amp;gt;.) at West Showa Zone, Oromia, Ethiopia

The field experiment was conducted in West showa zone, Toke kutaye district of Ormia region, Ethiopia with the objective to determine the optimum nitrogen fertilizer rate on different growth parameters, yield and yield component of tomato crop. To attain the objective, four level of nitrogen fertilizer Viz., 0, 50, 100, and 150 kg/ha were used as treatments. The experiment was laid out in randomized complete block design (RCBD) with three replications. Data on plant height, number of primary branches per plant, number of leaves per plants, number of cluster per plant, number of fruits per cluster and fruit yield were collected from five plants of the middle rows of each plot and subjected to statistical analysis software (SAS) version 9.3 and LSD at 5% was used for mean comparison. The statistical analysis showed that, there was the significant (P<0.05) difference among treatments for all parameters except for number of fruit per cluster. For growth variables, 150 kg/ha revealed the highest value but there was no significant (P<0.05) difference between 100 and 150 kg/ha of nitrogen except for the height of the plant. The treatment 150 kg/ha nitrogen fertilizer provided 22.41, 35.57 and 25.40% over the control treatment in height, number of leaves and number of primary branch, respectively. The treatment 150 kg/ha nitrogen fertilizer increased the number of cluster per plant and yield of tomato fruit per hectare by 34.50 and 70.79% over the control treatment, respectively. However, there was no significant difference in both number of cluster per plant and yield per hectare between 150 and 100 kg N/ha.

Influence of formulations of nitrogen fertilizes on oil flax productivity under conditions of western forest-steppe

The results of studies on the influence of forms and doses of nitrogen fertilizers (ammonium nitrate, urea, carbamide-ammonia mixture, ammonium sulfate) on the productivity of oil flax under the conditions of the western forest-steppe are given. In the traditional system of fertilizer, oil flax is not able to provide high yields and quality products. An effective solution to this is optimization of plant nutrition due to its balance, which promotes intensive plant development, makes it possible to actively and efficiently intervene in the process of harvesting and its quality. Therefore, determining the optimal fertilizer rate for oil flax in specific soil-climatic conditions is important for obtaining stable and high yields of culture. The purpose of our research was to determine the contribution of doses and forms of nitrogen fertilizers to the productivity of flaxseed oil in the soil-climatic conditions of the western forest-steppe. The research was carried out in 2016-2018 at the experimental field of the Institute of Agriculture of the Carpathian region of NAAS in five-point crop rotation with the total area of the plant growing on a gray forest surface glued type of soil In general, four forms of nitrogen fertilizers were studied: ammonia, nitrate, carbamide-ammonia mixture, urea and ammonium sulfate, which were added in doses: N30; N45 one time; and N30 + N15 under pre-sowing cultivation and in the "fir tree" phase against the background of P30K60. The total number of variants was 16. The object of research was a variety of flax oilseed crops of breeding of the Institute of Oilseeds of NAAS. The seed sowing rate is 6 mln similar seed per hectare. According to the results of three-year studies, the effect of intensification of mineral nitrogen feed and various forms of nitrogen fertilizers on the indices of the elements of productivity and yield of flaxseed oil has been established. In particular, it was found that their use had little effect on the density change of plant stem growth. The use of nitrogen fertilizers in the dose N45 on the background of P30K60 improved plant survival (killed during the vegetation of 0.33-0.42 million pp./ha, which is 5.2-6.3 % for control, where the death observed 0.58 million ppm/ha or 8.4 %)) compared to the N30 dose (0.39-0.49 million pcs/ha). In addition, the use of the dose N45 separately (N30 under cultivation + N15 in the phase of the "fir tree") also improved the survival rate of plants (5.2-5.8 % of dead plants) compared with the simultaneous application of N45 cultivation (5.6-7.1 %) The percentage of deaths grew in control (without fertilizers) - 8.4 % against the background of P30K60 - 7.0 %. The application of various forms and doses of nitrogen fertilizers led to an increase in the control of the elements of productivity. The introduction of N45 against the background of P30K60 contributed to an increase in the number of boxes on plants, according to the variants of fertilizers, this index varied from 14.6 to 18.3 pieces per plant (10.9 - on the control, 12.9 pcs/roll - on the РК background), increasing the amount of seeds per plant by 12.7 pc. per plant, a mass of 1000 seeds per 0.2-0.3 g compared with the control and 0.1-0.2 g compared with the LCD background, where this figure was 6.8 g. On average, over the years of research, the highest productivity of flax seed of oilseed Vodograi (2,27 and 2,48 t / ha) was obtained provided the mineral fertilizer N15P30K60 was applied for cultivation in combination with carbamide feed in the phase of "fir tree" at a dose of N15. When using the nitrogen component in the form of KAS, the gain to control was 1.45 t / ha, to the background - 1.12 t/ha. In control and against the background, this indicator was 1.04 and 1.36 t/ha respectively. When using other forms of nitrogen fertilizers on the background of P30K60, lower yields of flaxseed crops were obtained (1.37-1.38 t/ha). The introduction of the N45 separately (N30 under cultivation + N15 into the "fir tree" phase) generally led to higher performance than a single application for cultivation. Among the studied forms of fertilizers, urea and carbamide-ammonia also caused a slightly higher percentage of fiber content in flax stems, however, it was within the experimental error and was not significantly increased.

Fertilization and irrigation regimes influence on seedling attributes and field performance ofPinus tabuliformisCarr

Fertilization and watering are important nursery cultural practices for seedling production, though few studies have investigated the combined effects of fertilizer and watering rates on nursery attributes and field performance of container-grown pine seedlings. Four subirrigation rates ranging from 55 to 85 per cent gravimetric water content (θg) and three rates of controlled-release fertilizer (CRF) from 50 to 150 mg N·seedling⁻¹ were examined on Pinus tabuliformis in this study. Seedling attributes were assessed at the end of the nursery growing season. Field performance was monitored over four years. In the nursery, seedling shoot growth and N loading increased with CRF and subirrigation rates. Root mass, and total P and K content declined at 150 mg·N·seedling⁻¹ rate when combined with 55 or 65 per cent θg. After field planting, initial seedling attributes, especially root mass and plant P and/or K content, strongly affected seedling survival and growth. Maximum field survival and the largest seedlings were achieved at the combined rates of 100 mg N·seedling⁻¹ CRF and 75 per cent θg after four years. We concluded that optimal fertilization and irrigation rates should be considered together to produce P. tabuliformis container-grown seedlings with desirable seedling attributes for field performance.

Site‐Specific Covariates Affecting Yield Response to Nitrogen of Late‐Sown Maize in Central Argentina

Core Ideas We used linear mixed effects models to explore maize yield response to applied N. Final models accurately described the observed data (R2 = 0.93). Best models indicated that yield response to applied N depended on soil N and soil type. Information is useful to optimize management decisions on N fertilizer rates. Resulting models are better than traditional ones based on ordinary least squares. Optimizing fertilizer rates is a common problem in modern agriculture. Frequently used response models ignore basic statistical assumptions and do not allow quantifying the effects of variables influencing yield response to fertilizer, generating uncertainty in fertilizer rate recommendations. We used linear mixed‐effects models to explore maize (Zea mays L.) yield response to applied nitrogen (N) in late sowings, and we tested different predictors for explaining yield responses across sites. Data included yield response trials to applied N at 17 different environments (combination site × year) with four to five N rates replicated twice in each trial. The best model (Model A) that included significant effect of N rate applied, sowing date, and soil N‐NO3 at sowing described grain yield variations with high accuracy (R2 = 0.93). Another best model (Model B) showed that soil type as additional variable affected significantly yield response to applied N. The final model indicated that the overall response across sites was characterized by a linear coefficient of 67 kg grain ha−1 per additional kg N ha−1 applied and a quadratic coefficient of −0.37 kg grain ha−1 per additional kg N ha−1 applied. Across all sites, soil N‐NO3 at sowing (explored range from 34 to 356 kg N ha−1) explained 46% of the variability in the linear yield response to applied N. We proposed a method and generated statistical models with site specific covariates that can help optimize farmers’ decisions on the use of optimal N fertilizer rates.

Does the potential ammonium fixation of soils have an impact on the optimum nitrogen fertilizer rate?

ABSTRACTField experiments were conducted to determine the effect of nitrogen (N) fertilizer forms and doses on wheat (Triticum aestivum L.) on three soils differing in their ammonium (NH4) fixation capacity [high = 161 mg fixed NH4-N kg−1 soil, medium = 31.5 mg fixed NH4-N kg−1 soil and no = nearly no fixed NH4-N kg−1 soil]. On high NH4+ fixing soil, 80 kg N ha−1 Urea+ ammonium nitrate [NH4NO3] or 240 kg N ha−1 ammonium sulfate [(NH4)2SO4]+(NH4)2SO4, was required to obtain the maximum yield. Urea + NH4NO3 generally showed the highest significance in respect to the agronomic efficiency of N fertilizers. In the non NH4+ fixing soil, 80 kg N ha−1 urea+NH4NO3 was enough to obtain high grain yield. The agronomic efficiency of N fertilizers was generally higher in the non NH4+ fixing soil than in the others. Grain protein was highly affected by NH4+ fixation capacities and N doses. Harvest index was affected by the NH4+ fixation capacity at the 1% significance level.

Agronomic Evaluation of New Varieties of Cassava (Manihot esculenta Crantz) under Different Rates and Modes of NPK (12-12-17-2) Fertilizer Application in Two Seasons

A study was carried out at the Teaching and Research Farm of the Department of Crop Science, University of Nigeria, Nsukka to evaluate the growth and yield of four improved cassava varieties, determine their optimum NPK fertilizer rate and the best modes of fertilizer application for increased productivity. The experiment was factorial laid out in a randomized complete block design with three replications. Four varieties of cassava, four fertilizer rates and three modes of fertilizer application were used for the study. The early planting had higher survival count, number of leaves, tuber and garri yield when compared with late planting. The variety TMS 98 05 05 gave significantly (p&lt; 0.05) higher number of leaves, tuber and garri yields of 39.8 and 9.68 t/ha, respectively, at 12 months. At 6 months of crop growth, 200 kg/ha fertilizer application rate gave significantly higher tuber and garri yield of 24.69 t/ha and 5.15 t/ha, respectively. Furthermore, 400 kg/ha of NPK fertilizer rate gave higher tuber and garri yields of 39.4 and 10.12 t/ha, respectively at 12 months of crop growth. Split application of fertilizer gave significantly higher tuber and garri yield from single application, though it is statistically similar to split-split application. Therefore, early planting, 400 kg/ha fertilizer rate and split application should be adopted for cassava production. The variety TMS 98 05 05 with higher growth and yield should also be adopted by farmers for cassava production in Nsukka derived savannah agro-ecology.

Optimization of irrigation and N-fertilizer strategies for cabbage plasticulture system

Abstract Florida cabbage production is dominated by a bare ground production with sub optimal plant populations under seepage irrigation system. Previous studies used plasticulture to increase the plant population and maximize cabbage production per area. The present research was conducted to; determine the optimum nitrogen fertilizer application rate range, determine the transport and fate of applied nitrogen fertilizer and to examine the effects of two irrigation strategies for the proposed plasticulture system with high plant population. The soil moisture sensor based irrigation treatment used 11% and 33% less irrigation water in 2013 and 2014, respectively compared to the evapotranspiration based irrigation with no significant difference in cabbage yield. In 2014, the soil moisture sensor based irrigation also led to an increased retention time of nitrogen fertilizer in the crop rootzone. The optimum fertilizer rate range was determined to be between 400 and 570 kg ha−1 of N (5–7 g plant−1 of N), respectively. Cabbage yields obtained using fertilizer rates within the optimum range under high plant population plasticulture were on average 71% greater than the average bare ground yield under seepage irrigation.

Growth and Ethanol Yield Responses of Sweet Sorghum [Sorghum bicolor (L.) Moench] Varieties to Nitrogen Fertilizer Rates

Purpose: Soils of the experimental area are low in vital nutrients such as nitrogen. Fallow is no longer possible because of increasing pressure on arable land. The limited available chemical fertilizers must be inevitably and judiciously used for optimum yield. The study was carried out to assess the response of sweet sorghum varieties to varying nitrogen fertilizer (N) rates. Research Method: Sweet sorghum varieties (NTJ-2, 64 DTN, SW Makarfi 2006 and SW Dansadau 2007) were alloted to the main plots and nitrogen fertilizer (0, 40, 80, 120 and 160 kg N ha-1) to the sub-plots of a split-plot design, in three replicates. Data on growth and yield characteristics were collected and analysed. Findings: Variations were observed among the four varieties of sweet sorghum; SW Dansadau 2007 had greater growth and yield characteristics. N fertilizer had positive effects on the growth characteristics and ethanol yield of the crop. 80 kg N ha-1 resulted in increase of most parameters and ethanol yield, beyond which there was either no significant difference or a drop in the values of these parameters. Thus the use of 80 kg N ha-1 would result in optimum yield of sweet sorghum in the study area. Limitations: The requirement of 80 kg N ha-1 may not be generalized for the entire southern guinea savanna agro-ecological of Nigeria as the study was carried out only in one location. Originality/Value: These findings would assist farmers in the study area identify the most promising sweet sorghum variety and the optimum fertilizer rate for its production.

PENGARUH BERBAGAI TAKARAN PUPUK NITROGEN TERHADAP PERTUMBUHAN DAN HASIL TANAMAN CAISIN VARIETAS SHINTA

The objective of this experiment was to study the effect nitrogen fertilizer dose on growth and yield of Caisin plant (Brassica junceae L.) var. Shinta. An experiment was carried out at Experimental Station of Agriculture Faculty of Winaya Mukti University at Tanjungsari-Sumedang, with the altitude about 850 m above sea level, from February 2015 up to March 2015. Experimental design used was a Randomized Block Design (RBD), consisted of five treatment and each five replication. Dose of nitrogen (N) fertilizer tested namely : A = 0 kg ha-1 N, B = 10 kg ha-1 N, C = 20 kg ha-1 N, D = 30 kg ha-1 N, dan E = 40 kg ha-1 N. The result of this experiment showed that dose of nitrogen fertilizer be different influential on plant height at 28 Days After Planting (DAP) and 35 DAP, number of leaf at 35 DAP, weight of total dry matter per plant and weight of fresh per plant. Dose of nitrogen fertilizer 20 kg ha-1- 30 kg ha-1 give better effect on plant height at 28 Days After Planting (DAP) and 35 DAP, number of leaf at 35 DAP, weight of total dry matter per plant, and weight of fresh per plant. The optimum nitrogen fertilizer rate as much as 24.59 kg ha-1 give a weight per plant caisin maximum of 76.04 g

Integrated soil fertility management reduces termite damage to crops on degraded soils in western Ethiopia

Crop damage by termite is known to be severe in degraded soils. However, the role of organic inputs in reducing crop damage by termite has not been systematically studied in Ethiopia. Therefore, the objectives of this study were to quantify (i) the influence of integrated use of manure and NP fertilizer on termite damage and pod yields of hot pepper (Capsicum frutescence L.), (ii) the optimum rate of manure and NP fertilizer for hot pepper production for the study area, and (iii) the association between different rates of nitrogen (N) fertilizer and plant damage by termite. Two separate experiments were conducted for three consecutive seasons on degraded soils that were hotspots of termite activity. The treatments in experiment 1 consisted of different rates of well-composted manure applied in combination with NP fertilizer, whereas experiment 2 consisted of different rates of N fertilizer with basal application of 44kg Pha−1. In experiment 1, the combined application of manure and NP fertilizer significantly (P<0.05) reduced plant damage but increased pod yields compared with the control treatment and the recommended NP fertilizer. Plant damage by termites decreased from 29% in the first season to 11% in the third season, while pod yield increased from 378kgha−1 in the first season to 2339kgha−1 in the third season. The results of the repeated measures data analysis also indicated significant (P<0.0001) differences among the seasons in plant damage by termite and pod yield. In experiment 2, continuous application of the different rates of N fertilizer did not significantly reduced plant damage by termite while the N effect lacked consistency on pod yield. However, the application of N at rates ≥75 and >100kgha−1 increased termite damages to hot pepper in the first and second seasons, respectively. Overall, the application of one-fourth of the recommended NP fertilizer (25/11kgN/Pha−1) along with 10t manure ha−1 was found to be optimum for hot pepper production for the study area and similar agroecosystem. Therefore, we recommend adoption of the integrated use of manure and NP fertilizer to prevent soil degradation and reduce termite damage in western Ethiopia.