Agronomic effectiveness of partially acidulated phosphate rock fertilizers in an allophanic soil at near‐neutral pH

Abstract

The agronomic effectiveness of five partially acidulated phosphate rocks (PAPRs) and an unground phosphate rock (PR) were compared against single superphosphate (SSP) in a glasshouse experiment using a high phosphorus (P) retention soil at a near‐neutral pH (pH 6.5), and corn (Zea mays L.) as the test crop. The PAPRs were prepared by acidulating unground North Carolina PR with either phosphoric or sulphuric acid (expressed as Phos‐PAPR and SA‐PAPR, respectively) and at three levels of acidulation (20, 33, and 50%). The relative agronomic effectiveness (RAE) and substitution value (SV) of the test fertilizers, calculated with respect to SSP using the standard “vertical”; and “horizontal”; comparisons, showed that 50% phosphoric acidulated PAPR performed as effectively as SSP whereas the other fertilizers were less effective. The PR treatment showed a small yield response. The dry matter yield and P uptake were linearly related to water‐soluble P of the fertilizers up to 66% of total P and there was no advantage in acidulating fertilizers above this level of water‐soluble P using reactive PR. Whereas very little of the directly‐applied PR dissolved (3.4% of PR applied), PR applied as a component of PAPRs dissolved up to 22%. The dissolved proportion of added PR component increased with increasing water‐soluble P content of the fertilizer. The results suggest a greater efficiency of PAPR than SSP as a P supplier to plants.     

Unacidulated and partially acidulated Phosphate Rock as P sources in an acid Ultisol in the forest zone of southeastern Nigeria

The relative agronomic effectiveness (RAE) of phosphate rock (PR) and its 50% partially acidulatet form (PAPR) (less soluble P sources) relative to single superphosphate (SSP) and diammonium phosphate (DAP) (soluble sources) was studied in a two year field trial with maize in an acid Ultisol in the forest zone of southeastern Nigeria. All the P sources increased top growth, grain, and stover yields over the control. The RAE of PR relative to SSP was lower in the first year (25 and 38% for dry matter (DM) and grain yield (GY) respectively) compared to the second (64 and 58% for DM and GY respectively). Partial acidulation increased the yields by 17 and 7% for DM and GY, respectively, in the first year but not in the second. The RAE of PR and PAPR relative to DAP followed the same trend. The response curves of DM, and GY to rates of applied P showed that lower grain yields were produced in the first compared to the second year. The soluble and less soluble sources built up the Bray 1 extractable P to levels adequate for maize production in the agroecological zone.     

Agronomic evaluation of phosphorus fertilizers developed from sokoto rock phosphate in Nigeria

Abstract

Sokoto rock phosphate (SRP) obtained from Sokoto in the Northern Nigeria was evaluated with some other phosphorus (P) sources viz: Partially acidulated rock phosphate (PARP) and single superphosphate (SSP) in the greenhouse and field studies. These fertilizers were also compared with nitrogen‐phosphorus‐potassium (NPK) 11–12–11–9.7S‐1.4Zn and NPK 10–20–5–6.5S which have 80% of their P as rock phosphate and were formulated through compaction. The fertilizers were applied in the greenhouse at 0–400 mg kg^‐1soil on the Oyo Arenic Haplustalf and Alagba Kandiudult soil. Field trials were carried out at four locations—at Ikenne in the humid, Samara in the subhumid, Gumi and Gusau in the semi‐arid zones of Nigeria. The fertilizers were applied at 0–150 kg P₂O₅ ha^‐1 in the humid zone and 0–100 kg P₂O₅ ha^‐1in the subhumid and semi‐arid zones. Maize was used as test crop in most sites except at Samaru where sorghum was planted. The results of the greenhouse study showed that on the Haplustalf, PARP, and NPK 10–20–5–6.5S gave almost a similar relative agronomic effectiveness (RAE about 70%) as SSP, which was followed by SRP and NPK 11–12–11–9.7S‐1.4Zn (RAE between 50 and 60%). On the Kandiudult, the RAE of the fertilizers increased significantly. The PARP and NPK 10–20–5–6.55S gave high effectiveness (RAE about 90%) relative to SSP. The field trials results indicated that ground SRP was suitable for direct application on slightly acid soil in the humid zone (annual rainfall > 1,200 mm). Its efficiency was fairly moderate in the subhumid and quite low in the semi‐arid zones (annual rainfall <900 mm). The PARP gave higher RAE than SRP and had almost similar efficiency as for NPK 10–20–5–6.5S. The PARP was well comparable to SSP in the humid and subhumid zones and was fairly comparable to the later in the semi‐arid. This suggests that PARP may be suitable for humid and subhumid zones and the physical quality was also superior to SRP and SSP. Application of SRP on soils in the semi‐arid zones of low rainfall gave relatively low yields which could be due to inadequate moisture availability required to enhance P solubilization.     

不同施磷水平对土壤中重金属镉的钝化效果评价

通过室内培养试验,以P/Cd摩尔配比分别为0,2∶3,3∶2,2∶1,4∶1进行了不同磷肥钝化修复Cd污染土壤试验。采用毒性淋溶提取法(TCLP)和形态分析法评价了磷酸氢二铵(DAP)、磷酸二氢钾(MPP)、过磷酸钙(SSP)和磷酸钙(TCP)对污染土壤中Cd的钝化效果。结果表明,4种磷肥的钝化效果依次为:MPPDAPSSPTCP,4种磷肥的钝化处理可显著降低土壤中TCLP提取态Cd含量,在磷肥剂量水平P/Cd为4∶1时对土壤中Cd的钝化效果最佳,最大降低幅度为49%;添加磷肥能够大幅度提高土壤中速效磷的含量,相同磷水平下,土壤中速效磷含量高低次序为:MPPDAPSSPTCP,TCLP提取态Cd含量随土壤速效磷含量升高而显著降低(R=-0.903**);DAP,MPP,SSP和TCP处理后交换态Cd的浓度降幅分别为23.75%,39.06%,16.60%和18.36%,而碳酸盐结合态(WSA)、铁锰氧化物结合态(Fe-Mn-OX)、有机结合态(OM)和残渣态(RES)Cd的含量均有所升高,表明磷素是通过改变Cd的存在形态而降低其有效态含量的。     

Alleviation of Multinutrient Deficiency for Productivity Enhancement of Rain-Fed Soybean and Finger Millet in the Semi-arid Region of India

Soil nutrient contents were determined in 802 surface soil samples (0–15 cm deep) collected from farmers' fields that support extensive cultivation of soybean (Glycine max L.) and finger millet (Eleusine coracana G.), spread across three districts, in the semi-arid regions of Karnataka, India. Following soil analysis, on-farm crop trials were conducted during 2005–2007 to study the crop response to the soil application of nitrogen (N), phosphorus (P), sulfur (S), boron (B), and zinc (Zn) fertilizers. Analyses of soil samples revealed that 4–83% fields were deficient in N, 34–65% in P, 83–93% in extractable S, 53–96% in B, and 34–88% of farmers' fields were deficient in Zn. On-farm trials conducted during the three rainy seasons (2005, 2006, and 2007) significantly (P ≤ 0.05) enhanced crop productivity indices such as yields of grain, stover, and total biomass in soybean and finger millet crops. Integrated management of deficient nutrients in finger millet and soybean crops significantly enhanced the grain and straw uptake of N, P, K, S, and Zn.     

Effectiveness of Egyptian phosphate rock on clover production in Ethiopia

Abstract

The majority of soils in Africa are phosphorus (P) deficient, but the high cost of water‐soluble P fertilizers limits their use by resource‐poor farmers. A low‐cost alternative is to use phosphate rocks. We evaluated the effectiveness of Egyptian phosphate rock (EPR) relative to triple superphosphate (TSP) applied at 0, 15, 30, 45, and 60 kg P ha^‐1 to annual Trifolium species grown on a P‐deficient Vertisol. The fertilizers were applied once and their effects were followed on seven consecutive annual clover crops. Clover responded to P at all the rates used. Significant (P<0.05) P effects on clover P content and DM yields were observed up to the fourth crop. Over all the seven crops, EPR was 89% as effective as TSP in increasing herbage DM and 93% as effective in increasing herbage P content. Its substitution rates were 79% for DM yield and 86% for clover P content. Therefore, EPR was highly reactive and its use could elevate the P status of the P‐deficient Vertisols and increase feed and livestock productivity in the Ethiopian highlands.     

Impact of precursor crop and nitrogen fertilizer on the productivity of finger millet based cropping system and soil fertility in Lake Tana basin of Ethiopia

Abstract

Traditional short-term diversification of annual crops for the purpose of improving soil fertility and food security is a common practice in Ethiopia. However, the best cropping systems have not been selected yet though field research. Experiments were conducted for two years with an objective of establishing sustained finger millet based short term cropping sequence in two major finger millet producing areas of Ethiopia. The experiments were laid out in a split-plot arrangement with six precursor crops (haricot bean, maize, sweet lupine, niger seed, wheat, and teff) as a main plot factor, where determined residues were retained in the main plot after harvesting and two nitrogen fertilizer levels (30 and 60?kg ha^?1) applied for finger millet as sub-plots with three replications. Soil analysis result examined immediately after finger millet harvest showed a significant effect of precursor crops and nitrogen fertilizer rates on soil properties. Planting finger millet following lupine increased the soil organic carbon, total nitrogen and cation exchange capacity by 17.37%, 65.50%, 26.15%, respectively, over planting finger millet following teff. Use of different amount of nitrogen fertilizer likely contributed to observed differences in residual soil nutrients. Accordingly, finger millet following lupine with the addition of 60?kg ha^?1 nitrogen fertilizer gave significantly higher finger millet grain yield (3.24 tone ha^?1) and relative production (22.37%) and economic (40.7%) efficiency. This system with their high sustainability and multiple benefits can be readily accepted by the farming community.     

Effect of fertilizer treatments and planting time on the yield of some grain legumes of the benue river basins of Nigeria

A selection process for an ideal cover crop for yarn, maize, and cassava was initiated in 1993 cropping season in Makurdi, Nigeria. Four types of food legume crops grown locally were selected for the trials. The yield potentials of akidi (Phaseolus vulgaris), ground akidi (Sphenostylis stenocarpa), odudu (Phaseolus lunatus), and kafanji (Vigna unguiculata) were evaluated in two cropping seasons and under conditions where either no fertilizers, 50 kg nitrogen‐potassium‐phosphorus (NKP)/ha or 21 kg P/ha from single superphosphate (SSP) source were applied. The crops were planted in April and repeated in August of the same year in a 4 x 3 factorial in a split‐plot design. Fertilizer NKP generally increased the grain yield of all the crops significantly. The yield differences due to P fertilizers for odudu and akidi were not statistically significant (P=0.05). The P fertilizer resulted in significant increases in the grain yield of kafanji (from 1.113 to 1.7 mt/ha) and ground akidi (0.97 to 1.27). The biomass, root systems, and nodule yields were also increased proportionally by P application for all the legumes. No significant yield differences was observed between early and late crops in grain yield when no fertilizer was used. However, the crops produced about 30–40% less nodules, biomass, and root yield due to late planting (August).     

Effect of residual phosphate on yield of lowland rice in North Sumatera

Abstract

Greenhouse experiments were conducted at three locations to study the residual effect of phosphate on rice, grown successively for four seasons in North Sumatera, Indonesia. The soils used at the three locations were high in phosphate from continuous applications with phosphorus (P) fertilizers for 15 years. Rice (Oryzasaliva), variety IR‐64, was grown receiving treatments with 0, 50, 100, 150, and 200 kg ha^‐1 superphosphate. These treatments, replicated three times, were applied only to the first crop. At the end of each growing period, rice yield was determined and the soil analyzed for available and acid extractable P content by the Olsen and HC1 extraction methods, respectively. The results indicated that the high concentration in available or acid extractable P content in the first season had resulted in the highest rice yields. Rice yield of the second crop decreased and remained constant at this level through the fourth crop. The phosphate levels in soil appeared to show a similar trend as rice yields. Both available and HC1 extractable P decreased in soils in the second and third growing season to level off at the fourth season. Apparently the plants were able to satisfy their P requirements from these residual P contents in soil during the second through the fourth growing season. It can be concluded that the use of P fertilizers can be reduced substantially both in total and frequency of applications.     

Sorghum and soybean response to natural and modified phosphate rock on acid soils in Venezuela

Abstract

An agronomic evaluation of phosphate rock (PR) on acid soils of Guarico and Anzoategui States was conducted to measure the effect on soil available phosphorus (P), grain yields of sorghum (Sorghum bicolor (L.) Moench) and soybean [Glycine max (L.) Merr.], and P absorption by these crops. Field experiments were established using a complete randomized block design with three replications. The treatments used were: triple superphosphate (TSP), North Carolina phosphate rock (NCRPR), compacted NCRPR with TSP at 60–40% and 70–30% (NCRPR 60/40 NCRPR 70/30), compacted Venezuelan Monte Fresco phosphate rock 60–40% and 70–30% (MFPR 60/40, MFPR 70/30), finely ground Monte Fresco phosphate rock (MFPR), finely ground Navay phosphate rock (NPR), and a check plot with no P source added. Five rates were applied, 0, 50,100,150, and 200 P₂O₅/ha, broadcasted and incorporated prior to planting. A basic fertilization of N, K, S, Mg, and Zn was uniformly applied to ensure an adequate supply of these nutrients. Soybean seeds were inoculated with Bradyrhizobium japonicum. Soil samples were taken before planting and at harvest, and plant samples taken at critical growth stage (flowering) for tissue analysis, Crop grain yields were measured at 12% moisture content. The relative agronomic effectiveness (RAE) was calculted by the formula: RAE (%( = Yield of the rock ? Yield of check plot/Yield of TSP ? Yield of check plot × 100 Maximum yields in all cases were obtained with TSP, however, in most cases there were no statistically significant differences between TSP and NCRPR as received or compacted (60/40 and 70/30). The compacted Venezuelan phosphate rocks also gave significantly higher yield and RAE responses showing the potential of these P sources for annual crops in the country. The finely ground Venezuelan phosphate rocks increased yields and RAE as compared to the check plot, but they gave the lowest response of all P sources. Soil available P after harvest had a tendency to increase where any source of P was applied or when the rates increased. The increment in soil available P was more evident when TSP and NCRPR as received and compacted were used. The lowest increments were reached with finely ground Navay phosphate rock. Leaf P concentration values were between the sufficiency range, except for those treatment where Monte Fresco and Navay finely ground phosphate rocks were applied at the rate of 50 kg P₂O₅/ha and for the check plot.     

Critical Limit of Extractable Phosphorous in a Gleysol for Rice Production in the Senegal River Valley of West Africa

Abstract

Soil‐test correlation and calibration, a useful tool for fertilizer recommendations, has been little used in West Africa. Soils from a long‐term fertility experiment have been used to study the relationship between rice yields and soil extractable phosphorus (P) with Bray 1 and Olsen methods. The Cate and Nelson graphical method was used for critical limits of soil P determination. The critical limits of soil extractable P at 95% relative grain yield were 9 mg P for the Bray 1P and 17 mg P kg^?1 for Olsen P. The Olsen P was more correlated (r=0.63) with rice grain yields than Bray P (r=0.50), but a strong correlation (r=0.92) was also observed between the values of the two methods. Results indicate that at levels less than these critical levels of extractable P, P fertilizers should be applied to increase rice yields.     

Evaluation of phosphorus availability from three phosphorus sources in Nigerian soils

Abstract

In an attempt to search for a cheaper source of phosphorus (P), both for direct application and industrial use, three P fertilizers were evaluated in incubation and greenhouse studies. Indigenous Sokoto rock phosphate (SRP) imported, Togo rock phosphate (TRP), and conventional single superphosphate (SSP) were applied on three soil types namely Oxisol, Ultisol, and Alfisol at rates ranging from 0–800 mg P kg^‐1 soil. Evaluation of the P sources was conducted for 12 weeks in incubation study, and five weeks in the greenhouse using maize as test crop. Evaluation of direct application of SSP and SRP on an oxic paleudult was carried out in the field for three years. The results of incubation studies revealed in general, that P availability increased as fertilizer rates increased. The P availability was, however, greater when SSP was applied on the Alfisol than on the Oxisol and Ultisol. The rock phosphates on the other hand were more efficient on acid soils than on soils neutral in pH. Optimum P availability from the fertilizers was observed to occur predominantly between four and eight weeks of incubation. In the greenhouse study, SSP gave the highest cumulative P uptake and optimum rate of application was 200 mg P kg^‐1 soil, while optimum rate for rock phosphate was 400 mg P kg^‐1 soil. The agronomic effectiveness (EA) of the rock phosphates was about 40% relative to SSP on the Alfisol. The EA, however, for TRP and SRP was 120% and 160%, respectively, on the Oxisol, while on the Ultisol, SRP was equally effective as SSP and TRP had 65% effectiveness. The results of the field trial indicated that the SRP had 54%, 83%, and 107% agronomic effectiveness of SSP, respectively, in the first, second, and third year of cropping. Optimum rate for SSP and SRP application was considered to be 50 and 75 kg P₂O₅ ha^‐1, respectively.     

解磷细菌、磷酸岩和化肥对玉米和小麦轮作及其经济收入的影响

A two-year field study was conducted to test the effects of two phosphate-solubilizing bacteria (PSB), Pantoea cypripedii (PSB-3) and Pseudomonas plecoglossicida (PSB-5), inoculated singly or together with rock phosphate (RP) fertilization on maize and wheat cropping cycle by comparing with chemical P fertilizer (diammonium phosphate, DAP), mainly in the crop yield, soil fertility and economic returns. Inoculation of PSB together with RP fertilization increased the crop growth in terms of shoot height, shoot and root dry biomass, grain yield and total P uptake in both maize and wheat crops compared to the other treatments. Soil fertility in the context of available P, enzyme activities and PSB population in both maize and wheat crops was significantly improved with PSB inoculation together with RP fertilization compared to DAP treatment. The combined use of PSB inoculation and RP fertilization was more economical due to minimal cost and maximum returns. These results suggested that PSB inoculation along with RP fertilization would be an appropriate substitute for chemical phosphate fertilizer application in sustainable agriculture systems.     

Effectiveness of Panda Hills phosphate rock compacted with triple superphosphate as source of phosphorus for rape,wheat, maize,and soybean

Abstract

Greenhouse experiments were conducted to evaluate the agronomic effectiveness of Panda Hills phosphate rock (PPR) from southwest Tanzania, its mixture with triple superphosphate (TSP), and a compacted mixture of Panda PR and TSP (PPR+TSP) for wheat, rape, maize, and soybean on two United States soils (Hiwassee and Windthorst). The mixture of Panda PR and TSP was prepared by mixing ground TSP with Panda PR in proportions such that 50% of the total phosphorus (P) in the final mixture was from TSP. The compacted product (PPR+TSP) was prepared by compacting some of the blended mixture of Panda PR and TSP into pellets using a laboratory scale Carver press followed by crushing and screening. The P rates applied to Hiwassee soil were 0, 25, 50, and 100 mg P kg^‐1 for each P source and test crop while on Windthorst soil only one rate of application (50 mg P kg^‐1) was applied to one test crop (rape). A lime treatment was also included on the Windthorst soil to enable evaluation of rape response to the different P sources under calcareous conditions. Wheat and rape were allowed to grow to maturity while maize and soybean were grown for six weeks only. The performance of the P sources as reflected by yield, P uptake and relative agronomic effectiveness (RAE) followed the order TSP>>(PPR+TSP)>(PPR)+(TSP)>>PPR for wheat, rape, maize, and soybean on Hiwassee soil. Panda PR was very ineffective in increasing grain or dry‐matter yields of the test crops on this soil. The mixture of Panda PR and TSP as well as the compacted product increased wheat, maize, and soybean yields and P uptake significantly. The increases in yields were, however, largely attributed to the TSP component of the (PPR)+(TSP) mixture or its compacted product with little or no contribution from PPR. On the alkaline Windthorst soil, the performance of the P sources as reflected by rapeseed yield and RAE followed the order TSP= (PPR+TSP)>(PPR)+(TSP)>PPR. Remarkably compacted PPR and TSP was at par with TSP while PPR alone was 50% as effective as TSP in increasing rapeseed yield. Addition of lime drastically reduced the effective‐ness of Panda PR, but it had little or no effect on the agronomic effectiveness of the (PPR)+(TSP) mixture or its compacted product.     

Response of Different Crops to Arbuscular Mycorrhiza Fungal Inoculation in Phosphorus-Deficient Soil

Arbuscular mycorrhizal fungi (AMF) have the capability to improve crop yields by increasing plant nutrient supply. A pot experiment was conducted under natural conditions to determine the response of AMF inoculation on the growth of maize (Zea mays L.), sorghum (Sorghum bicolor L.), millet (Pennisetum glaucum L.), mash bean (Vigna mungo L.), and mung bean (Vigna radiata. L.) crops during 2008. The experiment was conducted as a completely randomized design in three replications using phosphorus (P)–deficient soil. Three plants were grown in 10 kg soil up to the stage of maximum growth for 70 days. Spores of AMF were isolated from rhizosphere of freshly growing wheat and berseem crops and mixed with sterilized soil with fine particles. Crops were inoculated in the presence of indigenous mycorrhiza with the inoculum containing 20 g sterilized soil mixed with 40–50 AMF spores. Inoculation with AMF improved yield and nutrient uptake by different crops significantly over uninoculated crops. Inoculated millet crop showed 20% increase in shoot dry matter and 21% in root dry matter when compared with other inoculated crops. Increases of 67% in plant nitrogen (N) and iron (Fe) were observed in millet, 166% in plant P uptake was observed in mash beans, 186% in zinc (Zn) was measured in maize, and 208% in copper (Cu) and 48% in manganese (Mn) were noted in sorghum crops. Maximum root infection intensity of 35% by AMF and their soil spore density were observed in millet crop followed by 32% in mash beans. Results suggest that inoculation of AMF may play a role in improving crop production and the varied response of different crops to fungi signifies the importance of evaluating the compatibility of the fungi and plant host species.     

Effects of Phosphorus Fertilizer Source and Plant Density on Growth and Yield of Maize in Northwestern Pakistan

ABSTRACT

Phosphorus (P) fertilizer source and plant density are considered some of the most important factors affecting crop growth and yield. A field experiment was conducted to determine the impact of P source [zero-P control, DAP (diammonium phosphate), SSP (single super phosphate), and NP (nitrphos)] and plant density (D₁ = 40,000, D₂ = 60,000, D₃ = 80,000, and D₄ = 100,000 plants ha^?1) on growth and yield of maize (Zea mays L cv. Azam) on a P-deficient soil (6.6 mg P kg^?1) at New Developmental Agricultural Research Farm, North-West Frontier Province (NWFP) Agricultural University, Peshawar, Pakistan, during summer 2006 in wheat-maize cropping system. Physiological maturity was delayed, plant height was increased and leaf area was decreased significantly when maize was planted at highest (D₄) than at lowest plant density (D₁). Application of SSP resulted in earlier physiological maturity of maize than other P fertilizers. Grain and stover yield, harvest index, shelling percentage, thousand grain weight and grains ear^?1 were maximized at D₃ (80,000 plants ha^?1) and with application of P fertilizer. Highest benefit in growth and grain yield was obtained with application of DAP to maize planted at D₃. Application of DAP at D₃ gave 15, 29, and 19% higher grain yield than its application at D₁, D₂, and D₄, respectively. In conclusion, the findings suggest that growing maize at 80,000 plants ha^?1 applied with DAP can maximize productivity of maize in the wheat-maize cropping system on P-deficient soils.     

Tughutu和Minjingu磷酸盐石作为豆类作物生长磷资源的农业和经济潜力研究

On-farm experiments were conducted in farmers＇ fields at 6 different sites in Western Usambara Mountains （WUM） in northern Tanzania during the 2000-2001 cropping season. The objectives were to study the effects of Tughutu （ Vernonia subligera O. Hoffn） pruning in combination with Minjingu phosphate rock （MPR） or triple super phosphate （TSP） supply on the concentration of P in the tissues and seed yields of common bean, and to assess the economic returns of these different technologies to farmers. The experimental design was a randomized complete block with each of the 6 farmers＇ fields used as a replicate. The treatments included： control, MPR or TSP each at 26 kg P ha^-1, Tughutu at 2.5 t ha^-1, and Tughutu at 2.5 t ha^-1 combined with MPR or TSP at 26 kg P ha^-1. Addition of MPR or TSP alone significantly raised P concentration in bean shoots from 1.27 mg g^-1 to 1.70 and 1.95 mg g^-1 respectively. Combining MPR or TSP with Tughutu increased P concentration above the proposed deficiency level of 2 mg g^-1. The relative agronomic effectiveness （RAE） of MPR ranged from 12.5% to 45.0%. Seed yields of common bean was markedly increased by 28%-104% from MPR or TSP supply alone, and 148%-219% from Tughutu application combined with 26 kg P ha^-1 of MPR or TSP relative to the control. With Tughutu alone, seed yield increased by 53%. From economic analysis, the increase in seed yield with the supply of MPR or TSP combined with Tughutu translated into a significantly （P ≤ 0.001） higher marginal rate of return and dollar profit for common bean farmers in WUM in northern Tanzania. It is concluded that Tughutu and its combined application with MPR or TSP is an appropriate integrated nutrient management strategy that may increase bean yields and dollar profit to the rural poor communities in Tanzania.     

EFFECT OF DIFFERENT PHOSPHORUS SOURCES ON THE GROWTH,YIELD, ENERGY CONTENT AND PHOSPHORUS UTILIZATION EFFICIENCY IN MAIZE AT RAWALAKOT AZAD JAMMU AND KASHMIR,PAKISTAN

Effect of poultry manure (PM) and four inorganic phosphorus (P) fertilizers sources, i.e., diammonium phosphate (DAP), single super phosphate (SSP), nitrophos (NP) and triple super phosphate (TSP) on crop production and P utilization efficiency (PUE) of maize was studied. Both inorganic P fertilizers and PM applied alone or combined in 50:50 proportions at equivalent rate of 90 kg P₂O₅ ha^?1. Results indicated that inorganic P sources with PM significantly increased plant height, leaf area and chlorophyll content. Average values showed that combined application of inorganic P with PM increased grain yield by 19 and 41% over inorganic P and PM alone, respectively. Similarly, increase in P-uptake due to the combined application of inorganic P + PM was 17% compared to sole inorganic P. Phosphorus utilization efficiency of inorganic P was increased with PM and the highest PUE was recorded in DAP + PM. Generally, combination of DAP + PM proved superior over the remaining P fertilizers.     

Agronomic Effectiveness of Partially Acidulated Phosphate Rock

Laboratorial incubation and field experiments were conducted on soils ranging in texture from sandy loam to clay and in pH from 3.6 to 9.0 to determine the agronomic effectiveness of single superphosphate (SSP).fused magnesium phosphate(FMP) and partially acidulated phosphate rock(PAPR) on 8 field crops.The results showed that the pattern of available P released from SSP was fixing-releasing-fixing-steady state,while that of PAPR was shortly fixing-slowly releasing-fixing steady state.And the PAPR,SSP and FMP were equally effective as judged by yield Puptake by phants and extractable P in soils after crop harvesting,The PAPR used as basal fertilizer was more effective than that as top dressing,and its residual effect was also obvious.     

Response of maize (Zea mays) to the application of foliar fertilizers in the Sudan and Guinea savanna zone of Nigeria

Soil fertility problems resulting in low maize yields in smallholder farms are common in the West African moist savanna. The effectiveness of commercial foliar fertilizers in improving maize growth and yield was evaluated in three savanna agro‐ecological zones of Nigeria in two steps. In step one, eight commercial foliar fertilizers were assessed in a greenhouse study with two soil types using maize (Zea mays L. cv. 2004 TZE‐Y POPDT STR C4). The treatments included a control and a reference that received the optimum concentrations of nutrients. In step 2, three promising products from the greenhouse study (Turbotop, Agroleaf General, and Agroleaf high‐P) were evaluated under field conditions to validate the efficacy of products to enhance crop growth and yield. The foliar products were applied at the rate of 5 kg ha^?1. The treatments also included three rates of P application (0, 30, and 60 kg P ha^?1) as triple super phosphate (TSP) with or without foliar fertilizers. In the greenhouse study, differences in maize shoot dry matter yield and N and P concentrations, attributable to the spraying of the commercial foliar fertilizers, were observed for both soils. Spraying Turbotop, Agroleaf General, and Agroleaf high‐P gave the highest shoot dry biomass and N and P uptake compared to other products. Under field conditions, foliar spraying of Agroleaf high‐P significantly increased the shoot dry biomass of maize compared with the 0 P treatment in all locations. The grain yield of maize ranged from 1 to 4 t ha^?1 with significant differences across sites. Products with high concentrations of P and N in their formulation improved maize yield suggesting that appropriate management of P and N resources is a prerequisite for a sustainable maize intensification in the savanna agro‐ecologies.