Recommended Fertilizer Rate Research Articles

Least-Cost Seed Potato Production in Ethiopia

Improved potato varieties can increase potato yields of smallholders, and thus contribute to food security improvement in Ethiopia. However, the uptake of these varieties by farmers is very limited so far and this is one of the causes of insufficient seed quality in the seed potato system in Ethiopia. The low uptake may be related to the high costs of recommended production methods for these varieties. The objective of this study was to formulate least-cost seed potato production methods for farmers in Ethiopia. The paper used integer linear programming to determine these least-cost seed potato production methods, using published data on the perceived contributions to seed tuber yield and quality of different cultivation and post-harvest management options, and calculated seed potato production cost data for the different options. For the potato-growing districts Jeldu and Welmera, several seed potato production methods were formulated from which farmers can choose an affordable method that will enable them to produce seed potato with reasonable yield and quality levels. Results showed that yield and quality levels could be simultaneously improved at relatively low extra costs, for example, by applying recommended fertilizer rate combined with two fungicide applications. In both districts, most methods were robust to 50% increases in the rental values of land, prices of seed, wage rates, and prices of agrochemicals. Findings can be used by potato development practitioners to advise farmers on the adoption of seed potato technologies that are compatible with their financial resources.

Unsustainability of recommended fertilization rates for coffee monoculture due to high N2O emissions

Industrial fertilization with an excess of mineral fertilizer leads to water pollution and global warming. For instance, high mineral fertilization rates in coffee plantations of Ecuador result in N losses, such as emissions of N2O, a greenhouse gas to the atmosphere. Therefore, we conducted here field experiments to optimize fertilization. We studied the effects of mineral fertilizers on soil fertility, N2O emissions, productivity, and profitability of monoculture coffee systems in Loja, Ecuador. During 2 years, treatments on plots of Coffea arabica included (1) low fertilization with 70 N, 22 P, and 31 K kg/ha/year first year and then 200 N, 65 P, and 62 K second year; (2) medium fertilization with 150 N, 44 P, and 62 K first year and then 300 N, 87 P, and 125 K second year; (3) high fertilization with 225 N, 65 P, and 93 K and then 400 N, 109 P, and 187 K second year; and (4) control plots without fertilizers. Results showed that, although medium-high fertilization rates recommended by experts gave high coffee yields and income, such treatments produced high N2O emissions and thus led to low production/N2O emissions ratios of 208 for medium fertilization, and of 188 for high fertilization. Low fertilization gave a high production/N2O ratio of 603, and an income of 7606 USD/ha higher than control, of 3524 USD/ha. Our findings demonstrate that rates based on expert recommendations from local extension services and usually applied by Ecuadorian coffee growers, such as our medium rate, fail to achieve a sustainable production. The application of approximately half the expert recommended rates, such as our low treatment, could allow an environmental and economic sustainability in monoculture coffee plantations of Ecuador.

English

Increasing fertilizer rates at sowing can provide significant increases in grain yield in vegetable crops. However, very high rates can impair root development because of increased soil salinization in the rows mainly because of KCl fertilizer. Broadcast fertilization without incorporation into soil may be a viable strategy to avoid this salinization. Therefore, we conducted a study to determine the effect of different fertilizer rates applied to the soil surface without incorporation on common bean grain yield and yield components in a no-tillage system. An irrigated field experiment with a randomized block experimental design with four replications was conducted in Brazil during the 2012 and 2013 growing seasons. The treatments consisted of four fertilizer rates of an N-P-K blend that were 0, 50, 100 (15 kg ha-1 of N, 90 kg ha-1 of P2O5 and 45 kg ha-1 of K2O) and 150% of the recommended fertilizer rate for in-furrow applications. Increasing broadcast fertilizer application provided a significant increase in common bean grain yield. The application of 300 kg ha-1 of fertilizer (100% of the recommended fertilizer rate) on the soil surface without incorporation provided a similar result as the application of the same amount in the seed row. The results document that broadcast application of a fertilizer blend on the soil surface without incorporation is a viable management tool to increase common bean grain yield in no-tillage systems in soil with high fertility, which is based mainly on its content of organic matter, phosphorus, and base saturation. Key words: Phaseolus vulgaris L., surface fertilization, Cerrado, no-tillage system.

Micro-Dosing of Lime, Phosphorus and Nitrogen Fertilizers Effect on Maize Performance on an Acid Soil in Kenya

<p>High cost of inorganic fertilizers and lime has precluded their use by smallholder farmers to remedy the problem of soil acidity and infertility in Kenya. To address the problem, we tested a precision technique referred to as micro-dosing, which involves application of small, affordable quantities of inorganic inputs on an acid soil in Busia County, Kenya. Experimental treatments were N-fertilizer (0 and 37.5 kg N ha<sup>-1</sup>), P-fertilizer (0 and 13 kg P ha<sup>-1</sup>) and lime (0, 0.77 and 1.55 tons lime ha<sup>-1</sup>). 37.5 kg N and 13 kg P ha<sup>-1 </sup>are 50% of the recommended fertilizer rates for maize production in Kenya while 0.77 and 1.55 tons lime ha<sup>-1</sup> are 25 and 50% of the actual requirement. Soil chemical changes, maize grain yield and nutrient recovery were determined. Lime and P-fertilizer significantly affected only the top-soil pH, Ca, Mg and available P, while the effects of N-fertilizer were evident on both top- and sub-soil N likely due to its faster mobility than P and lime. Grain P-fertilizer recovery efficiencies were 14 and 16-27% due to 13 kg P and 13 kg P + 0.77-1.55 tons lime ha<sup>-1</sup>, respectively. N-fertilizer recovery efficiencies were 37 and 42-45% due to 37.5 kg N and 37.5 kg N + 0.77-1.55 tons lime ha<sup>-1</sup>, respectively. Fertilizers applied to supply 37.5 kg N, 13 kg P and 0.77-1.55 tons lime ha<sup>-1 </sup>increased grain yield above the control by 134, 39 and 12-22%, respectively, therefore micro-dosing of these inputs can increase maize production on Kenyan acid soils.</p>

On-farm trials of optimal fertilizer recommendations for the maintenance of high seed yields in winter oilseed rape (Brassica napus L.) production

Mineral fertilizer plays an important role in the maintenance of high rapeseed yields during oilseed rape (Brassica napus L.) production. On-farm experiments at 60 sites throughout the Yangtze River Basin in China were conducted for 2 years to evaluate the effects of the recommended fertilization rates (180 kg N ha−1, 90 kg P2O5 ha−1, and 120 kg K2O ha−1) on the rapeseed yield, and three indices of soil nutrient supply were adopted to estimate the yield responses to fertilizer recommendation. The results showed that the average contributions of nitrogen (N), phosphorus (P) and potassium (K) fertilizer to seed yield were 40.4, 23.1 and 11.5%, respectively. Compared with the farmers’ fertilization practices (FFP), the recommended fertilization significantly enhanced the seed yield by 29.1% on average. The relationships between plant-available soil nutrient supply, seed yields of the nutrient omission treatments and the yield responses to fertilization were significant, rather than the results of soil testing. With plant-available soil nutrient supplies and seed yields increasing, the yield responses and fertilizer use efficiencies decreased. When the seed yields of no-N and no-P treatments were less than 2000 kg ha−1 and 1500 kg ha−1, the recommended fertilizer rate was beneficial for achieving high seed yield and high efficiency. As defined in our study, the recommended fertilization rates could be used as the regional mean optimal rates (RMOR) of fertilization for winter oilseed rape in the Yangtze River Basin. Partial adjustments according to crop nutrient uptakes and seed yields of the nutrient omission treatments will be feasible for the sites where they were nonresponsive to RMOR.

Effect of Poultry Manure and Different Combinations of Inorganic Fertilizers on Growth and Yield of Four Tomato Varieties in Ghana

The agronomic response of four tomato (Solanum lycopersicum L.) varieties to fertilizer application was examined at the CSIR-Crops Research Institute, Kwadaso-Kumasi in the Forest agro-ecological zone of Ghana during the 2013 growing season. The four tomato varieties Shasta, Heinz, CRI POO and CRI 034 were evaluated on five different fertilizer types using a split plot arrangements in randomized complete block design with three replications. The Tomato varieties were the main plots, with the fertilizer treatments as the subplots. The CSIR-CRI breeding lines (CRI P00 and CRI P034) were able to yield higher than the exotic varieties. Using Winner fertilizer (6 g/plant at two weeks after transplanting (WAT) ) and Sulfan (3 g/plant at 4 WAT) CRI P00 produced the highest yield (26.4 t/ha) followed by chicken manure (250 g/plant at 2 and 4 WAT) (23.1 t/ha). CRI P00 with Winner + Sulfan fertilizer application also produced significantly (p≤0.05) higher fruit yield (26.4 t/ha). Fertilizer application however did not have any significant effect on the days to flowering over the control.Fertilizer application however, increased the number of branching for the tomato plants with Unik15 + Urea having significantly more branches compared to the control. Results from this study showed that tomato yields in the Forest zones in Ghana can be increased using improved varieties and recommended fertilizer rates.

Optimization of fertilizer rate based on farmers’ practice in potato-hybrid maize relay cropping system

The experiment was conducted at the research field of Agronomy Division, BARI, Joydebpur, Gazipur during consecutive seasons of 2011-12 and 2012-13 to optimize fertilizer rate for potato hybrid maize relay cropping system. Seven treatments viz., T1= Farmers? fertilizer dose of potato (FFDP: N504P162K309 kg/ha) + Farmers? fertilizer dose of hybrid maize (FFDM: N0 P0 K0 kg/ha), T2= FFDP + 100% N of recommended fertilizer dose of hybrid maize (RFDM: N255 P55 K140 S40 Zn6 B2 kg/ha), T3= FFDP + 100% N & 25% others of RFDM, T4= FFDP + 100% N & 50% others of RFDM, T5= Recommended fertilizer dose of potato (RFDP: N198 P44 K194 S24 Zn6 B1.2 kg/ha) +100% N of RFDM, T6= RFDP +100% N & 25% others of RFDM, and T7= RFDP +100% N & 50% others of RFDM were tested on potato-hybrid maize relay cropping system. Potato (var. Diamant) and hybrid maize (var. BARI Hybrid Maize-9) were used in this experiment. Results indicated that yield of potato (28.38 - 28.83 t/ha) did not differ significantly but yield of hybrid maize (4.90 - 8.74 t/ha) varied significantly under different treatments. The higher grain yield (8.74 t/ha) of hybrid maize was recorded in farmers? fertilizer dose of potato or recommended fertilizer dose of potato (8.61 t/ha) along with 100% N plus 25% other fertilizers or 100% N plus 50% other fertilizers from recommended dose of hybrid maize. The highest potato equivalent yield (41.94 t/ha) and gross return (Tk. 335520/ha) were obtained from FFDP along with 100% N plus 25% others of RFDM (T3). But the highest gross margin (Tk. 219790/ha) and benefit cost ratio (3.01) were found from RFDP along with 100% N plus 25% others of RFDM (T6). The results revealed that recommended fertilizer rate of potato (N198 P44 K194 S24 Zn6 B1.2 kg/ha) along with 100% N plus 25% other fertilizers from recommended fertilizer rate of hybrid maize (N255 P55 K140 S40 Zn6 B2 kg/ha) might be optimum for potato hybrid maize relay cropping system for obtaining higher economic return. DOI: http://dx.doi.org/10.3329/bjar.v39i2.20443 Bangladesh J. Agril. Res. 39(2): 351-357, June 2014

Domestic sewage irrigation on dynamics of nutrients and heavy metals in soil and wheat (Triticum aestivum L.) production

Background Evaluation of urban sewage for its feasibility and potentiality as sources of irrigation water and plant nutrient is need of the hour. In this context, a field experiment was laid out in split‐split plot design with three replications. Main plots constituted two types of lands (fields irrigated with sewage and bore well water since 1992). Subplots were allotted with three sources of irrigation which consisted of sewage water alone, bore well water alone (good water) and conjunction of sewage and bore well water. And sub-subplot constituted of four fertilizer levels (no fertilizer, 50 % recommended rate of fertilizer (RRF), 75 % RRF and 100 % RRF. Results Crop growth in terms of photosynthesis, net assimilation rate and dry matter production significantly increased in sewage-irrigated land compared to bore wellirrigated land. Similarly, significantly higher wheat grain yield (4370 kg ha -1 ), protein (12.88 %) and dry gluten (9.22 %) were obtained in field irrigated with sewage water compared to bore well-irrigated land. Sources of irrigation also differed significantly producing higher grain yield (4,100 kg ha -1 ), protein (12.81 %), dry gluten (8.97 %) in sewage irrigation compared to bore well water irrigation. Enhanced activity of dehydrogenase and phosphatase enzymes and organic carbon in sewage-irrigated field contributed more to available nutrient pool of soil. Pooled results of 2 years revealed that wheat roots accumulated significantly higher amount of Cr, Ni, Pb and Cd in sewage-irrigated land compared to bore well-irrigated land. The same trend was noticed in stem with respect to Cr and Ni. In general, concentration of heavy metals was higher in root followed by stem and lower in grain. The Pb concentration in plant parts (root, stem and grain) was not influenced by land type and sources of irrigation. None of the treatments did show accumulation of these heavy metals in wheat plant parts more than normal range found in food plants. The values of these metals were below the recommended maximum tolerable levels proposed by the Joint FAO/WHO Expert Committee on Food Additives, Summary and conclusions. In: 53rd Meeting, Rome, (1999).

Farmer‐led maize biochar trials: Effect on crop yield and soil nutrients under conservation farming

AbstractIn extensive farmer‐led trials practicing conservation farming (CF) in three regions of Zambia (Mongu: sandy soils; Kaoma: sandy or loamy sand soils; Mkushi: sandy loam or loamy soils), we studied the effects of biochar made of maize cobs (0, 2, and 6 t ha−1corresponding to 0, 0.8, and 2.5% per basin) at different fertilizer rates of NPK and urea on crop yield of maize (Zea mays) and groundnuts (Arachis hypogaea). Conservation farming in this case combines minimum tillage (how basins), crop rotation and residue retention. For the first time, the effect of biochar onin situsoil nutrient supply rates [determined by buried Plant Root Simulator (PRS™) exchange resins] was studied, as well as the effects of biochar on elemental composition of maize. Effects of 0–10% (w:w) biochar addition on soil physical and soil chemical properties were determined in the laboratory. At all sites there was a consistent positive response in crop yield upon the addition of biochar. However, due to a great variability between farms there were no significant differences in absolute yields between the treatments. In the sandy soils at Mongu, relative yields (i.e., percentage yield with biochar relative to the same fertilizer rate without biochar) of maize grains and maize stover were significantly increased at recommended fertilizer rates (232 ± 60%) and at half the recommended rate (128 ± 6%), respectively. In addition, biochar significantly increased concentrations of K and P in maize stover.In situsoil nutrient supply rates as measured by PRS™‐probes were highly spatially variable with no consistent effects of the different treatments in the three regions. By contrast, the fraction of plant available water (Vol.‐%) significantly increased upon the addition of biochar in all three soils. The increase caused by 10% biochar addition was of factor 2.5 in Mongu (from 4.5% to 11.2%) and 1.2 in both Kaoma (from 14.7% to 18.2%) and Mkushi (from 18.2% to 22.7%). Cation exchange capacity, pH, and exchangeable K significantly increased upon the addition of 10% (w:w) biochar in all three regions with a subsequent increase in base saturation and decrease of available Al3+. Our findings suggest that the addition of biochar in combination with CF might have a positive impact on crop growth and that this positive effect is mainly caused by increases in plant‐available water and decreased available Al.

Optimizing nutrient management strategies for rice–wheat system in the Indo-Gangetic Plains of India and adjacent region for higher productivity, nutrient use efficiency and profits

Rice (Oryza sativa L.)–wheat (Trititicum aestivum L.) system (RWS) in South Asia is under stress, as nutrient removals by crops are higher than their replenishment through fertilizers. We evaluated improved nutrient management strategies at 10 different locations across the Indo-Gangetic Plains (IGP) of India and adjacent regions during 2003–04 to 2005–06, and compared the improved practices in terms of yield gain, nutrient use efficiency and economic returns, with existing farmers fertilizer practices (FFP), and state recommended fertilizer rates by the government departments (SR). Improved N–P–K application rates were calculated by accounting for the indigenous nutrient supply (INS), yield target and crop nutrient demand as a function of the interactions between N, P and K. Compared with the SR and FFP, improved practices increased average grain yield from 0.32 to 3.03 t ha−1 and 1.37–3.69 t ha−1 in rice, and 0.49–1.17 t ha−1 and 0.71–2.26 t ha−1 in wheat across the locations, respectively. Added net return (in US$) from improved practices over FFP and SR under RWS ranged from 219.6 to 804.9 and from 104.3 to 599 ha−1, respectively. Compared to improved practices, PFPN under SR and FFP were lower by 18.9 and 38.3% in rice, and 18.5 and 39.5% in wheat, respectively. Omission of P and K from improved nutrient management schedule resulted in yield loss of 0.6–2.8 t ha−1 in rice, and 0.43–1.84 t ha−1 in wheat, respectively. The annual removal of native P and K in the respective omission plots ranged from 21.8 to 46.1 kg P ha−1 and from 158.4 to 349.1 kg K ha−1. Application of 26 kg P and 99 kg K ha−1 under improved practices had synergistic effect on nutrient use efficiencies viz. PFPN, AEP, AEK, REP and REK. Results suggested that optimised nutrient supplies considering crop nutrient needs and INS have potential for improving yields, nutrient use efficiency and profits in RWS. The improved nutrient management strategy used in this study could be used in larger domains for improving cereal productivity, nutrient use efficiency and farm profits.

THE POTENTIAL USE OF ANAEROBIC BAFFLED REACTOR (ABR) EFFLUENT FOR PERI-URBAN HORTICULTURE

Currently under investigation by the eThekwini Water and Sanitation is the use of anaerobic baffled reactors (ABR) by local communities to treat wastewater. Studies undertaken at the University of KwaZulu-Natal, South Africa show that ABR effluent has the potential to improve soil nutrient status without adversely affecting soil properties. However, the availability of these nutrients for plant uptake up these nutrients has not been investigated and the effect on crop growth and yield is not known. This study aimed to (i) compare the use of ABR effluent as a fertilizer source and standard inorganic fertilizer recommendations for bean (Phaseolus vulgaris) and Swiss chard (Beta vulgaris) growth and; and (ii) determine the effect of high nutrient concentrations in ABR effluent on bean seed germination and seedling growth. Pot experiments were laid out for each crop species as a 3×3×2 factorial treatment structure using a completely randomized design with the following factors: soil type (3 levels - Inanda, soil from Newlands Mashu (Sepane soil form) and Cartref); Fertilizer application (3 levels - no fertilizer, recommended rate and half the recommended rate); Water (2 levels - ABR effluent and tap water, applied as ‘bucket’ irrigation). Obtained data indicated that Swiss chard plants grown at recommended fertilizer rates using tap water in irrigation did not differ significantly (P>0.05) with respect to dry matter accumulation and leaf area from those irrigated with ABR effluent at recommended and half rates in all three soil types. Bean seeds germinated using ABR effluent showed radicle protrusion earlier than those under tap water; radicles were longer and produced more root mass compared to those germinated using tap water. These findings suggest that the type of crop species and its nutrient requirements, stage of growth and development and the timing of application and soil properties would be important factors to consider when using ABR effluent. High P concentration (mg/L) in the ABR effluent may be associated with increased shoot mass and extensive root growth.

Meta-analysis of strategies to control nitrate leaching in irrigated agricultural systems and their effects on crop yield

Nitrate leaching (NL) is an important N loss process in irrigated agriculture that imposes a cost on the farmer and the environment. A meta-analysis of published experimental results from agricultural irrigated systems was conducted to identify those strategies that have proven effective at reducing NL and to quantify the scale of reduction that can be achieved. Forty-four scientific articles were identified which investigated four main strategies (water and fertilizer management, use of cover crops and fertilizer technology) creating a database with 279 observations on NL and 166 on crop yield. Management practices that adjust water application to crop needs reduced NL by a mean of 80% without a reduction in crop yield. Improved fertilizer management reduced NL by 40%, and the best relationship between yield and NL was obtained when applying the recommended fertilizer rate. Replacing a fallow with a non-legume cover crop reduced NL by 50% while using a legume did not have any effect on NL. Improved fertilizer technology also decreased NL but was the least effective of the selected strategies. The risk of nitrate leaching from irrigated systems is high, but optimum management practices may mitigate this risk and maintain crop yields while enhancing environmental sustainability.

Effects of leguminous plant residues and NPK fertilizer application on the performance of yam (Dioscorea rotundata ‘c.v.’ ewuru) in south-western Nigeria

The effects of cultivating and incorporating residues of previous tropical kudzu (Pueraria phaseoloides) and soybean (Glycine max) with application of NPK fertilizer on yam performance were evaluated at the teaching and research farm, LAUTECH, Nigeria. There were nine treatments: incorporation of legume residues (5 t DM ha−1), application of recommended fertilizer rate for yam (90–50–75 kg NPK ha−1) in the zone or 50% of recommended rate (45–25–37.5 kg NPK ha−1), alone and in combination with residues and a control without residues or fertilizer in a randomized complete block design. Cultivation of previous legumes reduced soil nematode population (>200%) compared with no legumes. For both years, application of Pueraria residues improved tuber yield by an average of 15.8% compared with control. Fertilizer application enhanced arbuscular mycorrhizal (AM) colonization of yam roots but AM colonization was lower (∼50%) in plots where Pueraria residues were incorporated compared with other plots. Combined application of plant residues with fertilizer improved soil organic carbon, total N, exchangeable Ca and Mg compared with application of NPK fertilizer. From these results, it is concluded that half of the recommended NPK rate may be adequate and incorporation of residues with reduced NPK fertilizer application may be a sustainable soil fertility management option for continuous yam production.

The effect of irrigation on nitrogen uptake and use efficiency of two willow (Salixspp.) biomass energy varieties

Hangs, R. D., Schoenau, J. J., Van Rees, K. C. J. and Knight, J. D. 2012. The effect of irrigation on nitrogen uptake and use efficiency of two willow ( Salix spp.) biomass energy varieties. Can. J. Plant Sci. 92: 563–575. Nitrogen (N) fertilizers historically have been applied to support increased productivity of purpose-grown willow (Salix spp.) biomass energy plantations. However, a frequently observed lack of willow growth response to added fertilizer N is often attributed to poor fertilizer use efficiency. The objective of this study was to determine the effect of irrigation on the recovery of broadcast15N-labelled fertilizer, applied during the final year of a 3-yr rotation, by two willow varieties. A split-split-plot experiment was established on a fertile heavy clay soil in Saskatoon, SK, Canada, which consisted of two willow varieties (Charlie and SV1), three irrigation treatments (no irrigation, 75%, and 100% field capacity), and two fertilization treatments (1× and 2× the recommended fertilizer rate of 100:30:80:20 N:P:K:S; kg ha−1). Irrigation increased fertilizer N uptake by Charlie, but had no effect on the amount taken up by SV1, which was attributed to greater N use efficiency of SV1 compared with Charlie when irrigated. Eighty-two percent of the applied fertilizer N was accounted for in the following sinks: 43% in the soil (0–60 cm), 31% in the willow tissues (i.e., stems, leaves, stump, and roots), 7% in the LFH layer, and <1% in the non-crop vegetation; the balance (approximately 18%) was presumed lost primarily through denitrification from the poorly drained soil, but possibly some may have leached below the root zone as well. Although the willow varieties accessed only a portion of the applied fertilizer N during the year of application, the majority of the residual fertilizer N was conserved within the production system and, therefore, remained available for willow uptake in subsequent years.

Potential of Bacillus cereus strain RS87 for partial replacement of chemical fertilisers in the production of Thai rice cultivars

There is increasing interest in the development of technologies which can reduce the requirement for chemical fertilisers in rice production. The objective of this study was to investigate the efficacy of Bacillus cereus strain RS87 for the partial replacement of chemical fertiliser in rice production. A greenhouse experiment was designed using different fertiliser regimes, with and without strain RS87. Six Thai rice cultivars were tested separately. Maximum rice growth and yield were obtained in rice receiving the full recommended fertiliser rate in combination with the strain RS87. Interestingly, all rice cultivars which were treated with strain RS87 and 50% recommended fertiliser rate provided equivalent plant growth and yield to that receiving the full recommended fertiliser rate only. A paired comparison between rice treated with 50% of the recommended fertiliser rate with the bacterial inoculant and the full fertiliser rate alone was further examined in small experimental rice paddy fields. Growth and yield of all rice cultivars which received the 50% fertiliser rate supplemented with strain RS87 gave a similar yield to that receiving the full fertiliser rate alone. Bacterial strain RS87 showed the potential to replace 50% of the recommended fertiliser rate for yield production. Integration of plant growth-promoting rhizobacterial inoculants with reduced application rates of chemical fertiliser appears promising for future agriculture.

Fertilizer, Irrigation, and Natural Ericaceous Root and Soil Inoculum (NERS): Effects on Container-grown Ericaceous Nursery Crop Biomass, Tissue Nutrient Concentration, and Leachate Nutrient Quality

We tested the effects of using an inoculum containing natural ericoid roots and soil (NERS) with two fertilizer and irrigation rates on plant growth, shoot (stems and leaves) nutrient concentration, leachate quality, and mycorrhizal colonization of container-grown Coast Leucothoe [Leucothoe axillaris (Lam.) D. Don] and Japanese Pieris [Pieris japonica (Thunb.) D. Don ex G. Don]. Uniform rooted liners were grown in 10.8-L containers in a pine bark, peatmoss, and sand (8:1:1 by volume) substrate medium in a randomized complete block design with four replications. A controlled-release fertilizer, Polyon® Plus 14-16-8 (14N–7P–6.6K), was incorporated in the substrate medium at the 100% manufacturer's recommended fertilizer rate [representing high fertilizer rate (HF)] (56 g per container) to supply 7.84 g nitrogen (N) and at 50% the manufacturer's recommended rate [representing low fertilizer rate (LF)]. Plants were irrigated using a cyclic drip irrigation system at high (HI) and low (LI) irrigation rates calibrated to supply 25.2 L of water and 16.8 L per week, respectively. On average, NERS inoculation increased shoot growth of Leucothoe and Pieris by 56% and 60%, respectively. Shoots of Leucothoe inoculated with NERS had higher N, phosphorus (P), magnesium (Mg), and manganese (Mn) concentrations than non-inoculated plants. At LF, nitrous-N (NOx-N) and orthophosphorus (PO4-P) concentrations in the leachate were reduced by 53% from Leucothoe and 62% from Pieris compared with HF-treated plants. A reduction of 37% and 36% in PO4-P concentration in leachates from Leucothoe and Pieris, respectively, were achieved at the reduced irrigation (LI) rate. The NERS inoculation reduced PO4-P concentrations in leachate from Leucothoe by 26% and NOx-N concentration by 33% in leachates from Pieris compared with non-inoculated plants. Compared with plants grown in the HI–HF treatment, the combination of LI–LF treatment reduced NOx-N concentrations in leachates from Leucothoe by 60% (P = 0.016) and reduced PO4-P leachate concentrations from Pieris by 72% (P = 0.0096). Decreasing the fertilizer rate to 50% of the recommended rate and the irrigation rate to 67% of the recommended rate in conjunction with the incorporation of NERS reduced leachate nutrient concentrations of two main water pollutants (NOx-N and PO4-P). Adopting the practice of adding NERS containing fungi and bacteria can be an effective system to increase shoot dry weight, allow reduction in fertilizer application, conserve water for irrigation, and minimize subsequent nutrient runoff in nursery operations.

Efficiency of Wheat Seed Production and Crop Diversification in Afghanistan

Production figures in 2008 showed that new private seed enterprises in Afghanistan produced and sold about 12,000 tons of certified wheat seed, which accounted for 95% of the total certified seed produced in the country. At a retail price of about US$1,200 per ton, the enterprises earned an average margin of 20%. When interviewed, the farmers ranked high yield as by far the most important characteristic they sought in improved varieties. Besides yield, the next important attributes were earliness, disease resistance, grain color, and bread making quality. Estimates of on-farm productivity showed that use of improved wheat varieties alone could contribute up to 33% incremental yield under irrigated conditions, whereas the use of quality seed could enhance yield further by 28%. These estimates were obtained under recommended fertilizer rates, in the absence of which yield levels would have declined substantially. Apart from wheat, other major crops the farmers grew varied by regions but in broad terms included rice, vegetables, maize, potato, cotton, barley, watermelon, and alfalfa.

Olive mill wastewater irrigation of maize: Impacts on soil and groundwater

Abstract The environmental impact of irrigating a maize field with weathered olive mill wastewater (OMW) for 5 years was assessed. The use of the weathered OMW added the following concentrations of nutrients to the field: 11.8 t/ha/yr carbon, 1033 kg/ha/yr total nitrogen, 23.8 kg/ha/yr phosphorous and 4161 kg/ha/yr potassium. The maize field received 6 times more nitrogen, 50 times more potassium and 2 times less phosphorous than the recommended fertilization rates. The presence of carbon increased microbial activity for organic nitrogen breakdown and the decomposition rate of organic nitrogen. No significant increase was observed of heavy metal accumulation in the soil. Electrical conductivity in the soil remained below the salinization threshold. No direct exposure values were exceeded. No impact on groundwater quality was observed. Irrigation of crops like maize with weathered OMW could be part of a viable decentralized solution for olive mill wastewater use in areas with low organic matter and high irrigation demand.

Integrated Organic-Inorganic Fertilizer Management for Rice Production on the Vertisols of the Accra Plains of Ghana

Studies were conducted at the Agricultural Research Centre, Kpong, of the University of Ghana, to find solution to the problem of low rice yields on the Vertisols of the Accra Plains. Rice yields from continuously cropped fields have been observed to decline with time, even with the application of recommended levels of inorganic fertilizers. The decline in yield has been attributed to low inherent soil fertility, which is partly the result of low levels of soil organic matter (OM). As part of the study, cow dung (CD) and poultry manure (PM) were separately applied to the soil at 20 t ha-1 solely and also 5, 10 and 15 t ha-1, in combination with urea fertilizer at 90, 60 and 30 kg N ha-1, respectively. Other treatments included a control and urea fertilizer at 30, 60, 90 and 120 kg N ha-1. There was a basal application of phosphorus and potassium to all plots at 45 kg P2O5 ha-1 and 35 kg K2O ha-1, respectively, based on the recommended fertilizer rate of 90 kg N ha-1, 45 kg P2O5 ha- 1 and 35 kg K2O ha-1, on the Vertisols of the Accra Plains. Studies were also conducted on the redox potential of CD, PM and rice straw (RS). The application of 10 t ha-1 CD and urea fertilizer (at 45 kg N ha-1) and 10 t ha-1 PM and urea (at 60 kg N ha-1) both gave paddy yields of 4.7 t ha-1, which did not differ significantly from the yield of 5.3 t ha-1, obtained under the recommended inorganic nitrogen fertilizer application of 90 kg N ha-1. This indicates a synergistic effect of OM and urea on soil fertility. The redox potential studies showed that RS had greater propensity to bring about reduced soil condition in paddy fields than CD and PM, while PM brought about greater reduction than CD.

The influence of N and P on maize yield and yield components in maize/rice mixture in the Northern Savanna Zone of Nigeria

Most recommended fertilizer rates available for crops in the northern savanna zone of Nigeria are for crops in monoculture. In order to be able to recommend to farmers the rates of nitrogen (N) and phosphorus (P) to be applied to maize and rice in an intercropping system to increase crop yields, a field experiment was conducted at the Samaru farm of the Institute for Agricultural Research (IAR), Nigeria (Lat. 11o 11’ N and Long. 07o 38’ E) at 680 m above sea level on a sandy loam soil in 1990 and 1992. Factorial combination of four levels of N (0, 60, 120 and 180 kg ha-1) and three levels of P (0, 13.2 and 26.4 kg ha-1) were laid out in a randomized complete block design (RCBD) with four replications. Yield components of maize such as ears/m2 increased significantly (P < 0.05) with increasing levels of N and P but no significant changes were observed in shelling percentage and 100 seed weight of maize. The number of panicles/m2 and number of tillers/plant were the yield components of rice that responded significantly (P < 0.05) with increasing levels of N and P. Threshing percent and 1000 seed weight of rice were not significantly affected by increasing levels of N and P. Grain yields of maize and rice increased significantly (P < 0.05) by raising the levels of N and P. The application of 13.2 kg P ha-1 at each level of N significantly (P < 0.05) increased maize and rice yields. However, the highest grain yields of both crops were obtained when 120 kg N ha-1 and 13.2 kg P ha-1 were applied.