Production potential and competitive indices of Indian mustard (Brassica juncea L.) based intercropping with wheat (Triticum aestivum L.) and lentil (Lens culinaris L.) under different row ratios of eastern Uttar Pradesh

A field experiment was conducted during the (rabi) seasons of 2009–2010 and 2010–2011 at the research farm, Department of Agronomy, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, to find out the suitable row ratio of Indian mustard (Brassica juncea L.) intercropping with wheat (1:9, 2:9, 1:6, 2:6) and lentil (1:4, 1:5, 2:4, 2:5) row ratios, respectively. The highest yield attributes of mustard were recorded with mustard + lentil (2:5), which was significantly superior to mustard + wheat (1:9) and mustard + lentil (1:5). Maximum seed yield and stover yield of mustard was recorded with mustard + lentil (2:4), which was being significant over other row ratios of mustard + wheat (1:6, 1:9, 2:9) but was at par with mustard + lentil (1:5) and mustard + wheat (2:6) row ratios. Mustard equivalent yield (3128 kg ha^?1) recorded under intercropping of mustard with wheat in 1:9 row ratio was significantly higher than sole cropping of mustard, wheat, and lentil, and other remaining intercropping systems. Intercropping of mustard with wheat in 1:9 row ratio showed the highest land equivalent ratio (1.51), aggressivity index (+0.15), net return (60,468 Rs ha^?1), and benefit:cost ratio (4.3) among all other intercropping treatments.     

Sustainable production of pigeon pea and sarpagandha (Rauvolfia serpentina) by intercropping

Sarpagandha (Rauvolfia serpentinaBenth. Ex Kurz.), a natural source of the alkaloid reserpine, is generally found growing under partial shade of deciduous forests in the tropics and subtropics. To promote its commercial cultivation under subtropical environment of the north Indian plains, a field trial was conducted during 2006–2009 to optimize the plant populations (row ratios) of pigeon pea and sarpagandha for higher productivity, land utilization efficiency and economic return in an intercropping system. Intercropping of two rows of sarpagandha with pigeon pea sown at a row distance of 90 cm proved highly beneficial in terms of total production (5.15 t ha^?1 grain and 10.27 t ha^?1 straw + stalk of pigeon pea and an additional dry root yield of 2.56 t ha^?1 of sarpagandha) from a unit area and time. The highest land equivalent ratio, LER (2.21), area time equivalent ratio, ATER (1.76), monetary equivalent ratio, MER (2.0), land-use efficiency, LUE (198%) and net return (Rs. 273,810 ha^?1) were obtained for the combination of pigeon pea and sarpagandha in 1:2 row ratio. Integration of two rows of sarpagandha as an intercrop with pigeon pea sown at 90 cm row distance is recommended for sustainable crop production.     

Production potential and economics of safed musli (Chlorophytum borivilianum) under intercropping system

A field experiment was conducted for two years, 2004–5 and 2005–6 during July–March at the research farm of the Central Institute of Medicinal and Aromatic Plants, Lucknow to study the compatibility, productivity and economics of intercropping in safed musli (Chlorophytum borivilianum Santapau & Fernandes). Vegetable crops viz cowpea, okra and bottle gourd, maize for grain, long duration pigeon pea, sweet basil in first year at their full and half population were intercropped with full population of safed musli in additive series. In the second year okra and sweet basil were replaced by lablab bean and sacred basil, respectively. Results of two years' experiments showed that intercropping of pigeon pea and bottle gourd with musli were advantageous in terms of overall yield, land equivalent ratio (LER), monetary advantage and economic return. The most appropriate combinations to realize the maximum advantage from intercropping were half plant population of bottle gourd grown at 100 × 100 cm or 120 × 90 cm spacing and pigeon pea grown at 120 × 20 cm spacing with musli. These combinations gave additional yield of 49.82 t ha^?1of bottle gourd and 6.51 t ha^?1 grain of pigeon pea (2-year mean) without significantly reducing the root yield of musli.     

Early Supplies of Available Nitrogen to Seed‐Row of a Canola Crop as Affected by Fertilizer Placement

Abstract

A field experiment was conducted at Star City (legal location SW6‐45‐16‐W2); Saskatchewan, Canada from May 2000 to June 2000, to measure nitrogen (N) and phosphorus (P) supply rates from fertilizer bands to the seed‐row of canola crop. Ion exchange resin membrane probes (PRS^TM) were used to measure N and P supply rates in four treatments [80 kg N ha^?1 of urea as side‐row band, 80 kg N ha^?1 of urea as mid‐row band, check/no N (side‐row)/P side‐row, check/no N (mid‐row)/seed placed P]. The treatments were arranged in a randomized complete block design with four replications. Two anion and cation exchange resin probes (PRS^TM) were placed in each plot in the seed‐row immediately after seeding and fertilizing. The probes were allowed to remain in the field for 2 days and replaced with another set of probes every 4 days for a total of 14 days until canola emerged. Ammonium‐N, nitrate‐N and P supply rates were calculated based on the ion accumulated on the probes. Urea side‐row band treatments (fertilizer N 2.5 cm to side of every seed‐row) had significantly higher cumulative available N supply rates than mid‐row band placement in which fertilizer N was placed 10 cm from the seed‐row in between every second seed‐row. No significant differences were observed in P supply rates. The higher N rates (120 kg N ha^?1) resulted in lower grain yield in side‐row banding than mid‐row banding possibly due to seedling damage. However, the earlier fluxes of N into the seed‐row observed with side‐row banding may be an advantage at lower N rates in N deficient soils.     

Effects of seed-placed sulfur fertilizers on canola,wheat, and pea yield; sulfur uptake; and soil sulfate concentrations over time in three prairie soils

The form of sulfur fertilizer can influence its behavior and crop response. A growth chamber study was conducted to evaluate five sulfur fertilizer forms (ammonium sulfate, ammonium thiosulfate, gypsum, potassium sulfate, and elemental sulfur) applied in seed row at 20 kg S ha^?1 alone, and in combination with 20 kg phosphorus pentoxide (P₂O₅) ha^?1, to three contrasting Saskatchewan soils. Wheat, canola, and pea were grown in each soil for 8 weeks and aboveground biomass yields determined. The fate of fertilizer was evaluated by measuring crop sulfur and phosphorus concentration and uptake, and supply rates and concentrations of available sulfate and phosphate in the seed row. Canola was most responsive in biomass yield to the sulfur fertilizers. Sulfate and thiosulfate forms were effective in enhancing soil-available sulfate supplies in the seed row, crop sulfur uptake, and yield compared to the elemental sulfur fertilizer. Combination of sulfur fertilizer with monoammonium phosphate may provide some enhancement of phosphate availability, but effects were often minor.     

EFFECTS OF CONVENTIONAL AND CONTROLLED RELEASE PHOSPHORUS FERTILIZER ON CROP EMERGENCE AND GROWTH RESPONSE UNDER CONTROLLED ENVIRONMENT CONDITIONS

A series of experiments on the effects of form and rate of seed row placed phosphorus (P) fertilizer were carried out under controlled environment conditions using flats of a P-deficient Brown Chernozemic soil from Saskatchewan, Canada. The experiments were conducted in the laboratory and growth chamber using rates of seed row placed granular P fertilizer up to 100 kg P₂O₅ ha^?1. Two forms of monoammonium phosphate fertilizer were compared: 1) conventional MAP granules and 2) controlled release phosphorus (CRP) fertilizer granules (Agrium Inc, Denver, CO, USA.) made with a polymer coating to slow the release of phosphate to soil solution. Six crops were utilized in the study to provide a range of commonly grown cereal, oilseed, pulse and forage crops in Western Canada: wheat (Triticum aestivum), canola (Brassica napus), mustard (Brassica juncea), flax (Linum usitatissimum), yellow pea (Pisum sativum) and alfalfa (Medicago sativum). Parameters measured were percentage of planted seeds that had emerged after two weeks, plant biomass yield, and plant P uptake after four weeks. Most of the crops tested showed no negative impact on emergence with seed row placed conventional P fertilizer at rates up to ～20 to 30 kg P₂O₅ ha^?1. Pea, flax and mustard tended to be most sensitive to injury from high rates of seed placed MAP while wheat was least sensitive. The controlled release phosphorus fertilizer (CRP) product greatly increased the tolerance of crops to high rates of seed row placed P, with rates of 80 kg P₂O₅ ha^?1 placed in the seed row producing no significant injury for most crops. This effect is attributed to the coating reducing the harmful salt effect that occurs when high rates of fertilizer are placed in the seed row in close proximity to the seed. Generally, a rate of 30 kg P₂O₅ ha^?1 was sufficient to produce maximum early season biomass yield and P uptake for both conventional MAP and CRP fertilizers. Large differences in early P availability were not evident between the conventional P and controlled released P fertilizer products.     

Type and placement of zinc fertilizer impacts cadmium content of harvested durum wheat grain

Due to potential international marketing concerns, North Dakota durum wheat (Triticum turgidum L. Desf.) producers require strategies that limit cadmium (Cd) in harvested grain. These trials were conducted in order to determine the impact of type and placement of zinc (Zn) fertilizer on harvested grain seed Cd levels and to determine the best timing of foliar Zn-ethylenediaminetetraacetic acid (EDTA). Foliar Zn-EDTA applied at Feekes 10 growth stage had the lowest grain Cd of 0.97 mg kg^?1 when evaluating different fertilizer sources and application timings. Application of 22.4 kg ha^?1 potassium chloride with the seed at planting resulted in the highest grain Cd of 0.151 mg kg^?1 and might be a concern when environmental conditions are conducive for Cd uptake from soil. Stepwise linear regression determined that soil pH and chloride explained 96% of the variability of grain Cd. Applying 1.1 kg Zn ha^?1 as foliar Zn-EDTA in combination with 33 kg nitrogen ha^?1 at Feekes 10.54 growth stage resulted in significantly lower grain Cd, and significantly higher grain Zn, iron, and protein content. Treatments that significantly lowered grain Cd did not decrease grain yield, test weight, or protein content. The treatments that most reduced grain Cd resulted in the most benefits from a production, marketing, and nutritional standpoint and represents an agronomic approach to biofortification of durum wheat.     

间作系统氮调控对小麦氮钾营养及条锈病发生的影响

通过探讨间作和施氮对小麦植株氮钾养分吸收、分配及条锈病发生的影响,明确氮钾养分吸收和分配与小麦条锈病发生的关系,以期为合理施肥实现控病增产提供理论依据。在云南安宁和峨山两地布置田间小区试验,研究3种施氮水平(0 kg×hm~(–2)、90 kg×hm~(–2)和180 kg×hm~(–2))和2种种植模式(小麦单作、小麦||蚕豆间作)对小麦植株氮钾含量与分配以及小麦条锈病发病率及病情指数的影响。结果表明,施氮增加了小麦产量,且间作增产效应显著;与单作相比,间作小麦平均显著增产31.9%(安宁)和18.0%(峨山);小麦||蚕豆间作产量优势明显,土地当量比为1.20～1.37(安宁)和1.16～1.27(峨山),但间作增产优势随施氮量增加而降低。施氮在提高产量的同时也加重了小麦条锈病危害,随施氮量增加,单、间作小麦条锈病的发病率和病情指数均呈增加趋势。间作有较好的控病效果,与单作相比,间作小麦发病率、病情指数分别显著降低9.6%～22.0%、23.7%～33.7%(安宁)和29.5%～36.5%、29.3%～39.6%(峨山)。施氮增加了小麦植株氮含量,且主要累积在叶片,叶片氮含量占氮吸收总量的41.3%～47.4%(安宁)和35.9%～44.1%(峨山);但间作显著降低小麦植株氮含量,并显著提高钾含量,因而显著降低了叶片氮/钾比。相关性分析表明,小麦条锈病发病率和病情指数与植株氮含量、叶片氮/钾比呈显著正相关,与钾含量呈极显著负相关。施氮增加了小麦植株氮含量,提高了叶片氮/钾比,进而加剧小麦条锈病发生;而间作则通过增加钾含量,降低小麦植株氮含量及叶片氮/钾比,平衡小麦植株内氮钾养分而增强小麦对条锈病的抗性。     

Yield and yield components of two irrigated red bean cultivars and some soil properties as influenced by wheat residues and nitrogen management

Crop residues are beneficial substances affecting crop production and soil properties. A field experiment was carried out to evaluate the effects of wheat (Triticum aestivum L.) residue rates (0, 25, 50 and 75%) combined with N levels (0, 34.5, 69, 103.5 kg ha^?1) on yield and yield components of two red common bean (Phaseolus vulgaris L.) cultivars and to monitor chemical soil parameters. The experiment was conducted at Research Center, College of Agriculture, Shiraz University, Shiraz, Iran for two years (2008–2009). The experiment was conducted as a split–split plot arranged in a randomized complete blocks design with three replications. The highest seed yield was obtained when 25–50% of residues were incorporated. The highest seed yield, seed weight per plant, 100-seed weight and seed number per pod were obtained with 103.5 kg N ha^?1 with no significant difference to 69 kg N ha^?1. Residue incorporation significantly increased soil organic carbon (SOC) as well as available K and P content. It is possible to sow red common bean as a double cropping by soil incorporation of 25–50% wheat residues with application of 69 kg N ha^?1.     

Cumulative Effect of Organic and Inorganic Sources of Nutrients on Yield,Nutrients Uptake and Economics by Rice–Wheat Cropping System in Indo-Gangetic Plains of India

ABSTRACT

Field experiments were conducted for 2 years in sandy loam soil, to study the direct effect of organic manures i.e. sewage sludge (SS), vermicompost (VC) and sesbania (SB) and chemical fertilizers on rice (Oryza sativa) and their residual effect on wheat (Triticum aestivum) grown in sequence in winter (Rabi) and summer (Kharif) season during 2015–2016 to 2016–2017 at Varanasi, Uttar Pradesh. Residual effect of organic sources of nutrients as SS, VC and SB were monitored up to fourth crop (II wheat) in sequence applied in conjunction with 75% recommended dose of fertilize (RDF). Among the nutrient sources, the maximum grain yield in I rice (4.89 t ha^?1), II rice (4.95 t ha^?1), was recorded in treatment T₃ (100% RDF with S, Zn, B) whereas in I wheat (4.68 t ha^?1) and II wheat (4.59 t ha^?1), it was recorded in T₄ (customized fertilizer). The maximum straw yield during all four crops was recorded in T₃ (100% RDF with S, Zn, B) in rice and T₄ (customized fertilizer) in wheat crop, which showed 25, 32, 23 and 28% increase over 100% RDF (T₂). Application of 100% RDF along with S, Zn, B and customized fertilizer increased the total uptake of N, P, K, S and B and also in net returns and B:C ratio followed by organic treatments.     

Silage yield and quality of row intercropped maize and soybean in a crop rotation following winter wheat

Maize (Zea mays L.) intercropped with soybean (Glycine max L.) may be a viable option to improve the quality of the silage. In this study, maize and soybean intercropped in different numbers of rows and their monocropping equivalents were tested to determine the best intercropping system in a crop rotation following winter wheat. The treatments were monoculture maize (M), monoculture soybean (S), 75% maize + 25% soybean (3M:1S), 50% maize + 50% soybean (2M:2S) and 25% maize + 75% soybean (1M:3S). The experiment was laid out in a randomized complete block design with three replications in 2011 and 2012 in Antalya, Turkey. Highest fresh forage yields were obtained from maize (53.3 t ha^?1) and 3M:1S (62.8 t ha^?1) treatments in 2011 and 2012, respectively. Maize treatment had highest dry matter yield (21.1 and 22.0 t ha^?1) in both years. Quality analysis of silage revealed that 3M:1S was superior to maize treatment in terms of dry matter (25.23%), crude protein (7.31%), crude fiber (18.27%), neutral detergent fiber (42.56%), acid detergent fiber (25.81%), lactic acid (4.71%) and acetic acid (4.05%). In conclusion, 3M:1S row intercropped production system was a better alternative for silage to monoculture maize in a crop rotation following winter wheat.     

Effect of Cattle Manure and Sulfur on Yield and Oil Composition of Pumpkin (Cucurbita pepo var. Styriaca) Inoculated with Thiobacillus thiooxidans in Calcareous Soil

The effect of cattle manure and sulfur fertilizer on seed yield and oil composition of pumpkin (Cucurbita pepo var. Styriaca) under inoculated with Thiobacillus thiooxidans was investigated in a factorial study based on a randomized complete block design. Experimental factors consisted of cattle manure (M) (M₀: 0, M₁: 10; and M₂: 20 t ha^?1), sulfur (S) (S₀: 0, S₁: 250; and S₂: 500 kg ha^?1) and T. thiooxidans (B): inoculated (B₁) and non-inoculated (B₀). Results demonstrated that the application of T. thiooxidans, cattle manure, and S fertilizer decreased the soil pH. The largest number of seed per fruit (367), highest fruit yield (70.57 t ha^?1), seed iron (Fe) content (16.26 mg 100 g^?1), and seed yield (111 kg ha^?1) was obtained when 20 t ha^?1 manure was applied in combination with 500 kg ha^?1 S inoculated with T. thiooxidans. In this condition, the content of S, Fe, phosphorus (P), and nitrogen (N) in plant shoots was increased by 44.8%, 22.58%, 33.89%, and 10.38%, respectively, compared to the control. Moreover, the highest content of seed protein was observed in 10 t ha^?1 manure and 500 kg ha^?1 S fertilizer inoculated with T. thiooxidans. When 250 kg ha^?1 S fertilizer was applied, 20 t ha^?1 manure decreased seed P content sharply. At the rate of 500 kg ha^?1 S fertilizer, the highest content of seed P was obtained from 20 t ha^?1 manure. Totally, 20 t ha^?1 cattle manure, along with 500 kg ha^?1 S fertilizer as well as T. thiooxidans inoculation, improved oil and seed yield of medicinal pumpkin.     

Effect of phosphorus placement on wheat yield and quality in Southwestern Buenos Aires (Argentina)

Abstract

In the Southwest of Buenos Aires Province (Argentina), wheat yields are limited by phosphorus (P) deficiencies in at least 50% of the area. The objective of this paper was to report on the relative efficiency of two different methods of application of ? fertilizer: (i) by row placement with the seed at sowing (RP) and (ii) by broadcasting and incorporation into the surface soil (BP). The design of the experiments was of complete blocks with a strip subplot. Treatments were ? rates and method of application. Subtreatments were ? fertilization at different times and rates. ? fertilizer was triple superphosphate (TSP). One experiment included diammonium phosphate (DAP). Yield response to ? was significant in 3 of the 4 experiments. The RP produced higher yields in three experiments, but differences were significant in only one site. The RP effects on yield are shown by comparison of yields for individual treatment rates and by the calculation of fertilizer efficiency, efficiency ratio and substitution rate (S), which is defined as the ratio of RP and BP rates rendering the same yield response. Of these, the substitution rate showed the most highly significant effects. Fertilizer efficiency for TSP broadcast ranged from 8 to 44 kg wheat kg^‐1 P. Efficiency ratio of RP to BP for a rate of 16 kg ? ha^‐1 was between 1.27 and 1.74. The S was significant in two experiments carried out on sandy loams where values of 0.31 and 0.39 were found for soils with 6 and 10 mg ? kg^‐1 (Bray I). In general, RP improved wheat quality as determined by kernel and volume weight and also the ability of the crop to compete with weeds (Avena fatua).     

Nitrogen Management for Sustainable Soil Organic Carbon Increase in Inceptisols Under Wheat Cultivation

Application of nitrogen (N) fertilizers to increase crop yield is a worldwide practice, which also has a positive influence on the soil organic carbon (SOC) increase. This study was carried out to investigate the dynamics of SOC and its fractions under different levels of N fertilization in wheat grown inceptisols of Northeast India over a period of 2 years. For the purpose of this study, fertilizer treatments with five N levels (40, 60, 72, 80, and 100 kg N ha^?1) were applied in randomized block design. Increased SOC particulate organic carbon (POC), humic acid carbon, and fulvic acid carbon were recorded under application of higher N. Stability of SOC as indicated by E4/E6 ratio and microbial biomass carbon (MBC) was higher on application of 72 kg N ha^?1. Among the SOC fractions, POC and MBC respond rapidly to different N fertilization rates. Available N and phosphatase activity increased while pH and urease activity (UA) decreased as a function of applied N fertilizer levels. Nitrogen fertilization increased wheat yield and biomass with insignificant differences among 100, 80, and 72 kg N ha^?1. Thus, under the present experimental conditions, application of 72 kg N ha^?1 can sustain SOC and soil health without compromising wheat yield in the inceptisols of Northeast India.     

小麦大豆间作条件下作物养分吸收利用对间作优势的贡献

采用田间小区试验和田间微区根系分隔试验 ,通过间作与相应单作成熟期氮磷钾养分吸收量和利用效率 (单位养分吸收量所能生产的干物质量 )的比较研究了小麦大豆间作中养分吸收和利用效率的变化。结果表明 ,间作作物氮、磷、钾养分吸收总量分别高出相应单作 24%～39% ,6%～27%和24%～64% ;而间作氮、磷和钾的利用效率分别比单作低5%～20%、5%～7%和 6%～32%。间作优势主要表现在养分吸收量的增加。间作大豆养分收获指数的提高使间作子粒产量优势比生物学产量优势更明显。种间根系分隔微区试验表明 ,间作作物养分利用效率的降低与两作物根系相互作用有关     

Effect of soybean inoculation with Bradyrhizobium and wheat inoculation with Azotobacter on their productivity and N turnover in a Vertisol

A long-term field experiment was conducted for 8 years on a Vertisol in central India to assess quantitatively the direct and residual N effects of soybean inoculation with Bradyrhizobium and wheat inoculation with Azotobacter in a soybean–wheat rotation. After cultivation of soybean each year, its aerial residues were removed before growing wheat in the same plots using four N levels (120, 90, 60 and 30 kg ha^?1) and Azotobacter inoculation. Inoculation of soybean increased grain yield by 10.1% (180 kg ha^?1), but the increase in wheat yields with inoculation was only marginal (5.6%; 278 kg ha^?1). There was always a positive balance of soil N after soybean harvest; an average of +28 kg N ha^?1 yr^?1 in control (nodulated by native rhizobia) plots compared with +41 kg N ha^?1 yr^?1 in Rhizobium-inoculated plots. Residual and direct effects of Rhizobium and Azotobacter inoculants caused a fertilizer N credit of 30 kg ha^?1 in wheat. Application of fertilizers or microbial inoculation favoured the proliferation of rhizobia in crop rhizosphere due to better plant growth. Additional N uptake by inoculation was 14.9 kg N ha^?1 by soybean and 20.9 kg N ha^?1 by wheat crop, and a gain of +38.0 kg N ha^?1 yr^?1 to the 0–15 cm soil layer was measured after harvest of wheat. So, total N contribution to crops and soil due to the inoculants was 73.8 kg N ha^?1 yr^?1 after one soybean–wheat rotation. There was a total N benefit of 13.8 kg N ha^?1 yr^?1 to the soil due to regular long-term use of microbial inoculants in soybean–wheat rotation.     

Broiler litter and inorganic fertilizer effects on seed yield and productivity of buckwheat and fenugreek in row intercropping

We present data of a 2 years field experiment on influence of intercropping and N source on yield and yield components of fenugreek (Trigonella foenum-graecum)–buckwheat (Fagopyrum esculentum) intercrops. The experiment was conducted at the research farm, College of Agriculture, Shahrekord, Iran during 2014 and 2015. Treatments included sole cropping of fenugreek (F), sole cropping of buckwheat (B), and three intercropping ratios. Second factor was N fertilizer type: mineral chemical fertilizer (CF) or broiler litter (BL). Intercropping improved yield of fenugreek and buckwheat compared with sole cropping and BL was the more effective fertilizer especially in intercrops. Fenugreek and buckwheat in intercrops used available environmental resources for increasing pods plant^?1, seeds pod^?1, 1000-seed weight, and harvest index (HI) (for fenugreek) and clusters plant^?1 and 1000-seed weight (for buckwheat) compared to the respective sole crops in both years. The resulting land equivalent ratios (LERs) of intercrops varied from 0.99 to 1.72 and the highest LER was observed in F:B = 2:1 treated with BL. This study shows a potential yield benefit of fenugreek–buckwheat intercropping under semiarid growing conditions when planting fenugreek and buckwheat at a ratio of 2:1, respectively, and applying BL compared with sole cropping with inorganic fertilizer application.     

Towards sustainable production of peppermint (Mentha piperita L.) through integrated use of vermicompost and cowpea green manuring with synthetic nitrogen fertilization

A field experiment with peppermint (Mentha piperita L.) was conducted in a sandy loam (Typic ustifluvent) soil during 2007 and 2008 at Lucknow, India. Ten treatments consisting of control (no synthetic or organic nitrogen fertilization), synthetic nitrogen fertilization (SN) 75, 150 and 225 kg ha^?1 alone, vermicompost (VC) 3 t + 37.5 kg SN ha^?1, VC 6 t + 75 kg SN ha^?1 and VC 9 t + 112.5 kg SN ha^?1 and intercropping of one, two and three rows of cowpea for green manuring in combination with 50, 100 and 150 kg SN ha^?1, respectively, were evaluated in a randomized block design. Integrated use of VC 9 t with 112.5 kg SN ha^?1 produced maximum essential oil (94.3 kg ha^?1), increased the herb and essential oil yields by 104 and 89%, respectively, over control and reduced SN use by 50%, without affecting the quality of essential oil. Application of VC and intercropping of cowpea for green manuring significantly improved the organic carbon, available N, P and K content in soil over SN alone. To get sustainable production of peppermint, application of VC 9 t ha^?1 along with 112.5 kg N ha^?1 through synthetic fertilizer is recommended for light textured sandy loam soils.     

Nitrogen fixation by annual forage legumes and its contribution to succeeding wheat in the Ethiopian highlands

Soil fertility is declining in most agro‐ecosystems in sub‐Saharan Africa, and incorporation of forage legumes into production systems to utilize the nitrogen fixed by the legumes could alleviate the problem, if efficient nitrogen‐fixing legumes are used. The amounts of nitrogen fixed by Lablab, Medicago, Trifolium, and Vicia species and their contribution to the following wheat crop were estimated in field experiments on an Alfisol at Debre Zeit in the Ethiopian highlands. The amounts of nitrogen (N) fixed ranged from 40 kg N ha^‐1 for T. steudneri to 215 kg N ha^‐1 for L. purpureus. The increase in grain yields of wheat following the legumes ranged from 16% for T. steudneri to 71% for M. tranculata where no N fertilizer was applied to the wheat. Additional N fertilizer applied to wheat at 60 kg N ha^‐1 had no significant effects on wheat grain or straw DM andN yields. In another experiment, eight lablab treatments consisting of factorial combinations of two cultivars (Rongai and Highworth), two Rhizobium inoculation treatments (inoculated and uninoculated) and two times of harvest (for hay at 50% flowering and for seed at seed maturity), were compared on lablab forage production and N yield, and residual effects on two succeeding wheat crops. Inoculation had no significant effects on nodulation, shoot DM or N yields. Rongai had significantly higher shoot DM and N yields than Highworth. Lablab harvested at flowering had significantly higher shoot DM and N yields than lablab harvested at seed maturity. Grain yields of the first wheat crop following the various lablab crops were 93–125% higher than grain yields of the wheat following wheat (continuous wheat) where no N fertilizer was applied. Therefore, lablab is a potential forage crop for incorporation into cereal production systems to improve feed quality and to reduce dependence on N fertilizers for cereal production.     

NITROGEN FERTILIZER MANAGEMENT FOR IMPROVED GRAIN QUALITY AND YIELD IN WINTER WHEAT IN OKLAHOMA

From 2002 to date, a long-term field experiment has been conducted at Lake Carl Blackwell, Oklahoma, with different rates and times of nitrogen (N) fertilizer application to determine their effect on grain yield, protein and N uptake of winter wheat. Trend analysis for N rates (0, 50, 100, 150 and 200 kg N ha^?1) and orthogonal contrasts for different application times (pre-plant, top-dressed in February and March) were performed. With increasing fertilizer N, wheat grain yield and protein content increased from 2110 kg ha^?1 to 6783 kg ha^?1 and from 8.96 to 17.19%, respectively. For grain yield, protein, and N use efficiency, split applications of N fertilizer were much more efficient than applying all N pre-plant. Large differences in grain yields were noted for different years at the same N rate (range exceeded 5.0 Mg ha^?1) and that illustrated the need for making within-year-specific N rate recommendations.