Response of three sorghum varieties to N supply and plant density in a tropical environment

Field trials were conducted at Samaru, Nigeria to investigate the growth, yield and grain quality response of three grain sorghum (Sorghum bicolor L. Moench) varieties (L. 187, SK 5912 and FFBL) to N fertilization under varying plant densities (33300, 50000 or 66600 plants ha^–1). Year × N interactions were significant for yield components and so were variety × N and variety × plant density interactions. Grain yield increased 41, 42, and 126% with application of 60 kg N ha^–1, the optimum N rate, a response which was associated with variations in grain weight per panicle, panicle weight and grain number. Varieties SK 5912 and FFBL produced more straw in response to added N than did var. L. 187 while yield components in var. SK 5912 and L.187 responded better than those in var. FFBL. Yield components declined in var. SK 5912 and L. 187 as plant density was increased to either 50000 or 66600 plants ha^–1. Grain crude protein (CP) content and protein yield were increased 8 and 52% respectively by 60 kg N ha^–1 but CP content declined as plant density was increased. Grain tannin content was virtually unaffected by increasing N supply. Optimum plant density for grain sorghum production in this environment is in the range of 50000 plants ha^–1.     

Effect of split application of phosphorus on the growth ofAzolla and low land rice

TheAzolla pinnata (Vietnam) inoculated in rice field 10 days after transplanting (DAT) at a rate of 500 kg ha^–1 fresh biomass along with phosphorus fertilizer application produced a mat on the water surface at 30 DAT. The three split application of phosphorus as 4.4, 2.2 and 2.2 kg P ha^–1 applied at 10, 15 and 20 DAT, respectively produced 67% more biomass and 57% more Nitrogen inAzolla than those obtained by applying 8.8 kg P ha^–1 at 10 DAT. Whereas, the two splits of phosphorus as 6.6 and 2.2 kg and 4.4 and 4.4 kg P ha^–1 applied 10 and 15 DAT, respectively produced 20 and 33% more biomass and 14 and 27% more Nitrogen only.The three split application of phosphorus also increased the grain and straw yields, panicle number and weight, nitrogen concentration and its uptake in rice significantly over application of the entire amount once only. An increase of 10% grain yield and 13% straw yields was observed when 8.8 kg P ha^–1 was applied in three splits rather than applied at one time. On the average an increase of 24% grain and 23% straw yields in rice were observed due toAzolla intercropping and 22% and 16%, respectively due to phosphorus application. The intercropping ofAzolla with rice along with phosphorus application also increased the fertility level of soil by increasing the total nitrogen, organic carbon and available phosphorus of soil.     

Mineral nutrition and fertilizer response of grain sorghum in India — A review over the last 25 years

Researches on the mineral nutrition and fertilizer response of grain sorghum (Sorghum bicolor (L) Moench) carried out during the last 25 years in India are reviewed here. In general, N,P,K, Fe and Mn concentrations in vegetative plant parts decreased with crop age, while the concentrations of Ca, Mg and Cu increased. The concentration of N and P increased in panicle or grains of sorghum with advance in crop age. The seasonal change for other nutrients has not, however, been studied.Accumulation and uptake of N,P, and K by grain sorghum were characterized. Usually N and P accumulated slowly compared with the rapid accumulation of K in early crop growth stage and vice-versa in later stages of growth. As against the sizable mass of N and P into panicle, K was partitioned into stalk.Fertilizer responses to N and P were observed throughout India. Improved varieties and hybrids of sorghum responded to N rates ranging from 60 to 150 kg N ha^–1, whereas a response to P application was observed up to 40 kg P ha^–1. Although responses to K application had been inconsistent, an increase in grain yield of sorghum was observed due to 33 kg K ha^–1. A balanced fertilizer schedule consisting of 120 kg N ha^–1, 26 kg P ha^–1, 33 kg K ha^–1 and 15–25 kg Zn50₄ ha^–1 is recommended for improved productivity of grain sorghum.It is concluded that systematic research efforts should be directed so as to identify problem soils showing deficiencies and toxicities of different nutrients. Characterization of the seasonal changes in the concentration and uptake of different nutrients and determination of critical concentration and hidden hunger of different nutrients in plant tissues would lead to the recommendation of balanced fertilization for different sorghum-growing regions in India.A part of the paper presented in the Silver Jubliee Conference of Indian Society of Agronomy held at H.A.U., Hissar (India) in March, 1981     

Yield and growth response to potassium of grain sorghum as influenced by variety in a savanna soil of Nigeria

Field trials were conducted at Samaru over a three-year period (1980–82) to study the yield, growth and nutrient concentration of three grain sorghum varieties (L. 187, SK5912 and FFBL) in relation to potassium fertilization in a savanna soil. Potassium application rates were 0, 25, 50 and 75 kg K ha^–1. Year × potassium interactions were not significant although there were significant variety × K interactions. The highest grain yields for var. L.187, SK5912 and FFBL occurred from the application of 25, 50 and 75 kg K ha^–1 respectively. Straw yield was generally increased by K application, which also promoted tillering and hastened flowering in grain sorghum. Although grain weight per head, head number per m², grain number and 1000-grain weight were unaffected by this nutrient, weight per head was reduced by 22.8 per cent. K application enhanced N concentration of sorghum plants but caused decline in P concentration. The highest K rate gave the highest K concentration in each of the three varieties at 7 weeks after planting. Optimum K requirement of grain sorghum would seem to be between 25 and 50 kg K ha^–1.     

Effects of different levels of chemical Nitrogen (urea) onAzolla and Blue-green algae intercropping with rice

Application of higher levels (60 and 90 kg N ha^–1) of nitrogen fertilizer (Urea) inhibited the growth ofAzolla pinnata (Bangkok) and blue-green algae (BGA) though the reduction was more in BGA thanAzolla. Inoculation of 500 kg ha^–1 of freshAzolla 10 days after transplanting (DAT) in the rice fields receiving 30, 60 and 90 kg N ha^–1 as urea produced an average of 16.5, 15.0 and 13.0 t ha^–1 fresh biomass ofAzolla at 30 DAT, which contained 31, 31 and 27 kg N ha^–1, respectively. The dry mixture of BGA (60%Aulosira, 35%Gloeotrichia and 5% other BGA on fresh weight basis) inoculated in rice field 3 DAT at a rate of 10 kg ha^–1 showed a mat formation at 80 DAT with an average fresh biomass of 8.0, 5.8 and 4.2 t ha^–1 containing 22, 17 and 12 kg N ha^–1, respectively with those N fertilizer doses.Application ofAzolla showed positive responses to rice crop by increasing the panicle number and weight, grain and straw yields and nitrogen uptake in rice significantly at all the levels of chemical nitrogen. But, the BGA inoculation had a significant effect on the grain and straw yields only during the dry season in the treatment where 30 kg N was applied. During the wet season and in the other treatments performed during the dry season no significant increase in yields, yield components and N uptake were observed with BGA.The intercropping ofAzolla and rice in combination with 30, 60 and 90 kg N ha^–1 as urea showed the yields, yield attributes and nitrogen uptake in rice at par with those obtained by applying 60, 90 and 120 kg N ha^–1 as urea, respectively but, the BGA did not. The analysis of soil from rice field after harvest showed thatAzolla and BGA intercropping with rice in combination with chemical fertilizer significantly increased the organic carbon, available phosphorus and total nitrogen of soil.     

Growth,yield components and micronutrient nutrition of field-grown maize (Zea mays L.) as affected by nitrogen fertilization and plant density

Growth and yield components in field-grown maize (Zea mays L.) were enhanced by nitrogen fertilization ranging from 50 to 200 kg N ha^–1. Ear diameter, kernel depth, grain: stover ratio, number of ears plant^–1, plant height and dry matter production increased as N fertilization rate was increased up to 100 or 150 kg N ha^–1. Tasselling in maize was hastened by N fertilization. Increasing plant density from 25000 to 75000 plants ha^–1 increased plant height, dry matter production and delayed tasseling but reduced ear diameter, kernel depth, grain: stover ratio and number of ears plant^–1. Increased N supply and plant density had no influence on the concentrations of Mn, Zn, Cu, and Fe in ear leaf; except that Mn concentration increased as N fertilization rate was increased up to 150 kg N ha^–1. Nitrogen × plant density interactions on the concentrations of the micronutrients in maize ear leaf were not significant.     

Growth rate,yield and nitrogen uptake response of grain sorghum (Sorghum bicolor (L) Moench) to nitrogen rates in humid subtropics

Field experiments were conducted during wet seasons (June to October) of 1974, 1976 and 1977 to determine the response of newly developed hybrids and varieties of grain sorghum to N fertilization under humid subtropical conditions of Pantnagar in India. In addition to the enhancement in flowering and maturity stages brought about by N application, it also resulted in increased plant dry weight, translocation coefficients, grain yield plant^–1 and grain yield ha^–1. Varietal differences existed with respect to their responses for yield and N uptake to N rates. Most of the entries responded up to 120 kg N ha^–1. Hybrid CSH 5 utilized applied N more efficiently than other varieties.Publication No 1612 of GBPUA and T, Experiment Station, Pantnagar.     

Phosphorus response of grain sorghum in the Guinea savanna of Nigeria as influenced by rates,placement and plant spacing

Improved grain sorghum (Sorghum bicolor L.) Moench responded to applied P up to 22 kg P ha^–1 on an Alfisol situated in the Nigeria savanna. Hill placement of phosphorus fertilizer gave higher grain yield of sorghum, one thousand grain weight, P content of leaves and residual phosphate than furrow P application. Grain yields were observed to be higher at population of 55 555 plants ha^–1 than at 31 750 and 24 700.     

Growth response,yield and yield components of upland cotton (Gossypium hirsutum L) as affected by rates and time of nitrogen application in the Nigerian savannah

Effects of rate and time of nitrogen fertilization on growth, yield and yield components of upland cotton (Gossypium hirsutum L) were studied in two years (1975–76). Four rates of nitrogen application (0, 26, 52 and 78 kg ha^–1) timed at 3 or 8 weeks after sowing were compared. Seed cotton yield components increased significantly with increased N application at least up to 52 kg N ha^–1, with yield increases between 49% and 73%. Seed cotton yield was influenced by treatments mainly through boll number. Both crop growth rate and fruiting were enhanced by nitrogen fertilization. Applying N at 8 weeks (flowering) favoured yield only slightly over that at 3 weeks (thinning), but improved crop growth and fruiting by about 64% and 24%, respectively. There were significant N rate × time interactions in favour of fertilization at flowering. Applying 52 kg N ha^–1 at 8 weeks seems best for cotton in the Nigerian savannah.     

Response surface analysis of the effects of seeding rates,N-rates and irrigation frequencies on durum wheat I. Grain yield and yield components

Interactive effects of nitrogen (N) rates, seeding (S) rates and irrigation frequencies on grain yield and yield components of durum wheat were studied for four years under field conditions at Tulelake, California. Each year the experiment was conducted using a split-plot design with 4 irrigation frequencies as main plots and combinations of 5 N-rates (0 to 360 kg/ha) and 5 S-rates (50 to 250 kg/ha) as subplot treatments replicated 4 times. A quadratic response surface model (RSM) was used to study the effects of these treatments on grain yield and yield components (tillers/area, kernel number/spike, kernel weight/spike and 100-seed weight). The RSM was very effective for analysis and data reduction for estimating the optimum combinations of N and S for maximizing the grain yield and yield components. The N utilization and uptake efficiency increased with each irrigation treatment and peaked at irrigation treatment C. Both N and uptake utilization efficiency decreased with each increment of N-rate.In most cases, the effect of irrigation was independent of N and S. One irrigation at tillering increased grain yield and yield components significantly over only a preplant irrigation. The response of additional irrigations were comparatively small and significant only in some cases. Both N and S had significant effects on grain yield and yield components, however, the response of N was larger than that of S. With increasing N-rate, grain yield and tiller number increased with the expected peak beyond 360kg N ha^–1 but the increments beyond 180 kg N ha^–1 were of progressively smaller magnitude. The kernel number and kernel weight per spike also increased with N-rate giving a peak between 270 and 360 kg N ha^–1. With increasing S grain yield and tiller number/area increased while kernel number and kernel weight per spike decreased progressively. It was impossible to maximize yield and yield components at a given combination of N, S, and irrigation. According to the model, grain yield and tiller number were maximized at the highest level of N and S, while kernel number and kernel weight/spike were maximized at the lowest S (50 kg ha^–1) and about 314 kg N ha^–1 under adequate water supply. On the basis of the findings of this study and output of the model, 180–360 kg N ha^–1, 150–250 kg S ha^–1 and two post-sowing irrigations (at tillering and at boot stage) in addition to a preplant irrigation was recommended for optimum yield. An additional irrigation might be required depending on the weather conditions during the grain filling period.     

Using mucuna and P fertilizer to increase maize grain yield and N fertilizer use efficiency in the coastal savanna of Togo

To reduce severe soil degradation associated with agriculture an intensified land-use system is being promoted in West African countries. Most soils of the West African savanna zones are so poor that the efficiency of mineral fertilizers, if applied, is very low. For this reason and because of their high cost and unavailability, many small-scale farmers are reluctant to apply fertilizer. This work investigates a fertilizer management strategy using integrated soil fertility management with a leguminous cover crop (mucuna) so as to improve the soil fertility and increase the use efficiency of fertilizer. The experiment was conducted in the coastal savanna of Togo at Djaka Kopé. The aim was to evaluate the effectiveness of mucuna short fallow (MSF) in increasing maize grain yield through an improved use efficiency of mineral fertilizer. A 2-year maize–mucuna relay intercropping system was compared with continuous sole maize cropping. Fertilizer treatments were factorial combinations of 0, 50 and 100 kg nitrogen (N) ha^–1 and 0, 20 and 40 kg phosphorus (P) ha^–1. While maize grain yield was significantly increased by N fertilization, P did not show any important effect on grain yield. With no N and P applied, grain yield after MSF was on average 40% (572 kg ha^–1) higher than without. The response to N was much greater than the response to MSF, indicating that N was undoubtedly the key element for maize yield building. P fertilization and MSF together positively influenced the apparent N recovery fraction (NRF). N uptake alone did not reflect on its own the yield obtained, and the relationship between grain yield and N uptake is shifted by MSF, with the grain yield increase per unit of N uptake being higher with than without MSF. Combining MSF and P fertilization may therefore lead to improved N use efficiency, making the application of fertilizer N (lower rates) more attractive to small-scale farmers.     

Nitrogen response of maize under temporary flooding

The adverse effect of temporary flooding on maize (Zea mays L.) yields and the nitrogen management required to mitigate the effect of flooding were studied for five years in field experiments on Choa sandy loam soil.Maize yields decreased with increase in duration of flooding and with decrease in the age of the crop at the time of flooding. Flooding periods exceeding 48 hours caused significant crop damage. The loss in yield on account of flooding was, however, less in 40-day old crops. A 24 hours flooding decreased grain yield by 17.7 and 3.9 per cent in 20-day and 40-day old crops respectively. Maximum yield loss amounted to 1.23 t ha^–1 of grains with 72 hours of flooding of 20-day old crop indicating that a younger crop is more prone to the deleterious effect of flooding.The nitrogen content of grains decreased significantly with increase in flooding period. A supplemental dose of 7 kg N ha^–1 as urea spray significantly increased grain yield. Soil application of supplemental nitrogen at the rate of 14 or 20 kg N ha^–1 enhanced the maize yield by 0.7 to 0.9 t ha^–1 under temporary flooded conditions. Spraying with urea solution increased nitrogen removed by the crop.Successive increments of 60 kg N ha^–1 gave an additional yields of 1.23, 1.01 and 0.41 t ha^–1 over the crop that received no nitrogen. Flooded maize responded to even higher rates of N fertilization than the dose of 120 kg N ha^–1 which is recommended in this region.     

Response of two okra (Abelmoschus esculentus L. Moench) varieties to fertilizers: Yield and yield components as influenced by nitrogen and phosphorus application

The response of two okra (Abelmoschus esculentus L. Moench) varieties (White velvet and NHAE 47-4) to fertilization in northern Nigeria was examined using four rates of nitrogen (0, 25, 50 and 100 kg ha^–1) and three rates of phosphorus (0, 13 and 26 kg ha^–1). Nitrogen application significantly increased green pod yield, pod diameter, number of fruits per plant, number of seeds per pod and pod weight. Application of phosphorus also significantly increased green pod yield, pod number and number of seeds per pod. The two varieties responded to nitrogen application differentially with respect to green pod yield. For optimum green pod yield of White velvet 35 kg N ha^–1 is suggested while for variety NHAE 47-4, N fertilization can be increased to 70 kg ha^–1. There was no differential response of varieties to phosphorus fertilization for green pod yield; however, the application of 13 kg ha^–1 enhanced the performance of both varieties.     

Fertilizer requirement of rice-wheat and maize-wheat rotations on coarse-textured soils amended with farmyard manure

Field experiments with rice-wheat rotation were conducted during five consecutive years on a coarse-textured low organic matter soil. By amending the soil with 12t FYM ha^–1, the yield of wetland rice in the absence of fertilizers was increased by 32 per cent. Application of 80 kg N ha^–1 as urea could increase the grain yield of rice equivalent to 120 kg N ha^–1 on the unamended soil. Although the soil under test was low in Olsen's P, rice did not respond to the application of phosphorus on both amended and unamended soils. For producing equivalent grain yield, fertilizer requirement of maize grown on soils amended with 6 and 12 t FYM ha^–1 could be reduced, respectively to 50 and 25 per cent of the dose recommended for unamended soil (120 kg N + 26.2 kg P + 25 kg K ha^–1). Grain yield of wheat grown after rice on soils amended with FYM was significantly higher than that obtained on unamended soil. In contrast, grain yield of wheat which followed maize did not differ significantly on amended or unamended soils.     

Response of two okra (Abelmoschus esculentus L. Moench) varieties to fertilizers: Growth and nutrient concentration as influenced by nitrogen and phosphorus application

The growth response and nutrient concentration in okra (Abelmoschus esculentus L. Moench) as influenced by four nitrogen rates (0, 25, 50 and 100 kg ha^–1) and three phosphorus rates (0, 13 and 26 kg ha^–1) were examined using two varieties (White velvet and NHAE 47-4). Nitrogen application generally increased fruit and shoot dry weights markedly whereas phosphorus increased them only moderately. Leaf and primary branch production and plant height were also enhanced by nitrogen fertilization up to 100 kg N ha^–1 but were not influenced by phosphorus application. The application of nitrogen enhanced the concentration of N, P and K in fruits and N and Mg in leaves while P and K concentrations in leaves were depressed. Nutrient concentrations in plant tissues were also partly a function of plant age and variety.     

Response of lowland rice and common bean grown in rotation to soil fertility levels on a Varzea soil

Brazil has approximately 30 million hectares of lowland areas, known locally as Varzea, but very little is known about their fertility and crop production potential. A field experiment was conducted for three consecutive years to evaluate response of lowland rice (Oryza sativa L.) grown in rotation with common bean (Phaseolus vulgaris L.) on a Varzea (low, Humic Gley) soil. Rice was grown at low (no fertilizer), medium (100 kg N ha^–1, 44 kg P ha^–1, 50 kg K ha^–1, 40 kg FTE-BR 12 ha^–1), and high (200 kg N ha^–1, 88 kg P ha^–1, 100 kg K ha^–1, 80 kg FTE-BR 12 ha^–1 fritted trace element-Brazil 12 as a source of micronutrients) soil fertility levels. Green manure with medium fertility was also included as an additional treatment. Average dry matter and grain yields of rice and common bean were significantly (P < 0.01) increased with increasing fertilization. Across the three years, rice yield was 4327 kg ha^–1 at low fertility, 5523 kg ha^–1 at medium fertility, 5465 kg ha^–1 at high fertility, and 6332 kg ha^–1 at medium fertility with green manure treatment. Similarly, average common bean yield was 294 kg ha^–1 at low soil fertility, 663 kg ha^–1 at medium soil fertility, 851 kg ha^–1 at high fertility, and 823 kg ha^–1 at medium fertility with green manure treatment. Significant differences in nutrient uptake in bean were observed for fertility, year, and their interactions; however, these factors were invariably nonsignificant in rice.     

Residual effects of growing mungbean and uridbean on the yield and nitrogen uptake of a succeeding wheat crop

A two year field experiment was carried out at the Indian Agricutural Research Institute, New Delhi - 110012, India to assess the effect of mungbean (Vigna radiata L.) and uridbean (Vigna mungo L.) residues on the yield and N uptake of a succeeding wheat crop as compared to sorghum fodder. Sorghum produced 3.5–7.5 times more dry matter and removed 2–3 times more nitrogen than mungbean or uridbean during same duration (80 ± 10 days) of their growth. Without N application the grain yield of wheat following mungbean and uridbean (without residue incorporation) was 0.45 and 0.48 t ha^–1 more than the yield of wheat following sorghum fodder. These yields were equivalent to that predicted when 36 and 38 kg urea-N ha^–1, respectively, was directly applied to wheat. The residual effects of these grain legumes were higher when succeeding wheat was fertilized with 60 kg urea-N ha^–1; at this level mungbean and uridbean spared 52 and 43 kg urea-N ha^–1, respectively, in succeeding wheat. The residual effect of mungbean and uridbean further increased when their residue was incorporated in soil; with this practice they spared 94 and 115 kg urea-N ha^–1, respectively, without N application to wheat and 74 and 82 kg urea-N ha^–1, respectively, with an application of 60 kg urea-N ha^–1 to wheat.Mungbean and uridbean, without residue incorporation, increased aboveground plant-N uptake of succeeding wheat by 11.5–34.9 and 10.8–34.0 kg N ha^–1, respectively; whereas with residue incorporation, they increased aboveground plant-N content of succeeding wheat by 26.1–45.8 and 32.7–47.7 kg N ha^–1, respectively.The results of the present study indicate that there is both an indirect sparing effect and a direct residual effect of mungbean and uridbean on the nitrogen needs of succeeding wheat, more so when their residues are incorporated in soil.     

Fertilization of tropical rice: A case study on Bangkok plain

This study consisted of a survey on the nutritional status of rice plants in relation to nutrient application and yield in 70 farmers' fields in four provinces of Bangkok plain during the 1977 wet season. In addition a series of fertilizer experiments were carried out on rice experimental stations in the same provinces to study yield response to N and P fertilization and to develop a fertilizer recommendation system based on plant analysis.The average grain yield in the survey was 3.2 t ha^–1 and the early (high yielding varieties), medium (local) and late maturity (local) types yielded 3.3, 2.8 and 3.0 t ha^–1, respectively. The average amount of fertilizers applied to these maturity types were 33, 15 and 7 kg N ha^–1 and 15, 8 and 6 kg P ha^–1, respectively. Regression analysis indicated only a slight correlation between yield and any level of fertilizer application. On experimental stations yields over 6 t ha^–1 were obtained with applications of N over 100 kg ha^–1 and P over 22 kg ha^–1. Evaluation of nutritional status of plants based on plant analysis showed that in all provinces there were strong and widespread nutrient deficiences primarily of N and secondarily of P, and possibly of some other nutrients. Fertilizer application based on plant analysis gave high yield responses. It was concluded that the major constraints of yield on Bangkok plain are too low fertilizer application especially of N, and unbalanced fertilization of N and P.     

Fertigation versus broadcasting in an orange grove

A long-term experiment was carried out in a mature orange grove comparing broadcasting versus continuous application of nitrogen at three rates (80, 160, 280 kg ha^–1), 22 kg P ha^–1 and 126 kg K ha^–1 annually. The trees were irrigated with minispriklers wetting 70% of the soil area.The level of NO₃-N in the leaves varied according to the rate of N application. Leaf K and P content were not affected by fertilization. High N applications caused excess N in the soil solution. The rate of N application did not affect orange yield, fruit size or quality. Fertigation at 160 kg N ha^–1 caused higher yields than when the same amount of fertilizer was broadcast. At the high application rate, no differences between modes of application were found.This study was initiated by A. Bar-Akiva, who died suddenly early in 1986. Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No 2104-E, 1987 series.(deceased)     

Penicillium bilaji and phosphorus fertilization effects on the growth,development, yield and common root rot severity of spring wheat

A strain ofPenicillium bilaji Chalabuda (PB) has recently been commercially released as a seed inoculant to increase phosphorus (P) uptake by wheat (Triticum aestivum L.). The purpose of this study was to compare the effects of drill applied P (15 kg P ha^–1) with PB seed inoculation on early growth, development, P uptake, and grain yield of Stoa spring wheat at four sites in North Dakota.Fertilization with P consistently enhanced early season growth, main stem development, tillering and P uptake. Seed inoculation with PB had little or no effect on these traits. Phosphorus fertilization tended to increase common root rot severity (CRR, incited byCochliobolus sativus (Ito & Kurib) Drechs.), while PB inoculation had no effect. Grain yields were significantly increased by P fertilization at one location. Inoculation with PB also increased grain yield at this location. The reason why PB inoculation increased yield at this location is not evident, as plant growth and P uptake were not enhanced earlier in the season. Averaged across all four sites, PB inoculation increased wheat yields 66 kg ha^–1, which is similar to averaged yield responses reported from the Prairie Provinces of Canada.