Levels Of Phosphorus Application Research Articles

Evaluating chickpea varietal performance under different levels of phosphorus application

Chickpea, a vital legume crop, faces yield limitations due to factors like climatic conditions, nutrition deficiency in soil etc. Therefore, the knowledge of adoptive varieties to prevailing climatic conditions and enhancement yield by nutrient management is essential. The present investigation was carried out to assess the effect of varying levels of phosphorus on growth and yield of chickpea, at Agricultural Research Farm of SGRR University, Dehradun during Rabi season of 2022-23. The treatments of experiment comprise two chickpea varieties viz., PG-186 (V1) and Type 9 (V2) and five levels of phosphorus application i.e., 0, 15, 30, 45 and 60 kg P2O5/ha which were replicated thrice in factorial randomize design. The growth and yield parameters were recorded during different crop growth stages to get the response of treatments. The recorded data shows that the variety Type 9 perform better than variety PG-186 in most of the growth and yield attributing characters. Among the phosphorus doses the application of 45 kg P2O5/ha was perform best among all other treatments. The interaction effects of variety Type 9 with 45 kg P2O5/ha (V2T4) showed maximum growth and yield attributing characters over the other treatment combinations like plant height (46.66 cm), number of branches per plant (5.67), dry matter accumulation in plant (30.67 g), 1000 seeds weight (140.00 g) and seeds yield per hectare (14.30 q/ha). Based on experimental findings it can be concluded that variety Type 9 with application of 45 kg P2O5 /ha is best among all other treatments for higher yield of chickpea at Doon valley of Uttarakhand.

Impact of sowing date and level of phosphorus application on economic returns in cotton.

This study explored the economic dynamics of cotton (Gossypium hirsutum L.) production in Msilale village, Chato District, Tanzania. The experiment utilized a factorial design with sowing dates on November 25th, December 15th, and January 4th, and phosphorus levels at 0, 20, 40, and 60kg P ha-1, replicated three times. Results indicated significantly higher cotton yields (6.1t ha-1 and 6.3t ha-1) for November and December sowings compared to January (3.8t ha-1). This is a 61% and 66% increase in cotton yields for November and December sowings, respectively relative to January sowing. Though not significant, 20kg P ha-1 and 40kg P ha-1 applications yielded 5.8t ha-1 and 5.4t ha-1, respectively, while 60kg P ha-1 yielded 5.3t ha-1. This is a 9.4% and 1.9% increase in cotton yields at 20 and 40kg P ha-1, respectively relative to absolute control and 60kg P ha-1 application. Economic analysis revealed that late sowing (January) had the lowest net profit (Tshs. 3,723,400 ≈ USD 1,486) and benefit-to-cost ratio (BCR) of 11.2. Early sowings recorded higher net profits (Tshs. 6,679,527 ≈ USD 2,666 and Tshs. 6,861,283 ≈ USD 2,738) and BCRs (18.4 and 18.8, respectively). This is a 79% (BCR = 64%) and 84% (BCR = 68) increase in net benefits from early sowings compared to late sowing. Applications of 20, 40, and 60kg P ha-1 resulted in net benefits of Tshs. 5,452,572 ≈ USD 2,176 (BCR = 19.2), Tshs. 5,209,904 ≈ USD 2,079 (BCR = 15.1), and Tshs. 5,748,786 ≈ USD 2,294 (BCR = 14.1), respectively, with a significant (p = 0.017) BCR at 20kg P ha-1 indicating cost-effectiveness. This is a 36% and 7.1% economic benefit at 20 and 40kg P ha-1, respectively compared to 60kg P ha-1 application. Optimizing sowing dates and P levels can boost economic returns in cotton production and promote sustainability.

Response of Spring Maize to Different Sowing Schedules and Phosphorous Application

A field experiment was conducted at the Agronomy Farm, School of Agriculture, Lovely Professional University in 2023 to assess the performance of maize (Zea mays L.) under varying sowing schedules along with levels of phosphorus application. The experimental site featured sandy loam soil with pH of 7.34, 0.32% organic carbon content, and an electrical conductivity (EC) 0.423 ds m-1. An experiment comprised different phosphorus levels, including recommended diammonium phosphate (DAP), recommended single superphosphate (SSP), 10% increase in DAP, or 10% increase in SSP applied at three sowing dates. It followed a randomized block design with twelve treatments and three replications. The results indicated that the timing of sowings had a significant impact on all yield attributes, such as cob length (cm), number of rows/cob, number of cobs/m2 area, grains/cob, grain yield (q/ha), biological yield (kg/ha), and harvest index (%). However, levels of phosphorus application did not exhibit a significant effect on growth and yield attributes. The best results, including taller plants (213.8 cm), a higher number of cobs per m2 area (14), increased number of rows/cob (16), grains per cob (334.7), grain yield (45.2 q/ha), biological yield (97.8 q/ha), and harvest index (53.2 %), were achieved by sowing maize crop at the optimum sowing date (D2).

Quality of Reclaimed Domestic Water Irrigated Peppers - NPK Coupling Model and Optimized Combination Solution

Focusing on the coupling between the NPK content in Reclaimed domestic water irrigated peppers and capsaicin, a field experiment in the three-factor, five-level quadratic general revolving combination design was conducted for an in-depth analysis of capsaicin content coupling model by testing the significance of regression equation and coefficient with regression equation. The test result shows that : (1) factors affecting the content of capsaicin are in order of nitrogen fertilizer application level (x1) > nitrogen fertilizer application level (x2) > potassium fertilizer application level (x3) according to the main factor effect analysis based on the established capsaicin-NPK coupling model; (2) the nitrogen-potassium interaction effectively improves the content of capsaicin. That is, the content of capsaicin theoretically tend to be 0g.kg-1 when both the nitrogen fertilizer application level and the level of potassium fertilizer application level are at the lowest; when the amount of nitrogen and potassium fertilizers application increases, the content of capsaicin increases accordingly. Medium nitrogen combined with medium potassium may result in the highest level of capsaicin content which can reach 0. 068g.kg-12 when the level of nitrogen and potassium fertilizers application reaches 120 g.kg-1 and 112.5g.kg-1 respectively . Under the circumstance of certain volume of potassium fertilizer application, the content of capsaicin further increases with the decrease in the level of phosphorus application. The maximum capsaicin content of 0. 21g.kg-1 is achieved when the level of potassium and phosphorus fertilizer application reaches 120 kg.hm-2 and 60 kg.hm-2 respectively; and (3) the range of the ideal target content of capsaicin in peppers irrigated with the reclaimed domestic water in China’s Ningxia Region and the optimized NPK combination solution are obtained and developed. And in specific: the level of NPK fertilizers application would be 186.15kg.hm-2, 71.17kg.hm-2 and 122.02kg.hm-2 respectively under the condition that the content of capsaicin being greater and beyond 0.12g.kg-1.

Dependence of pea root mass distribution on weather conditions under varying levels of phosphorus application

Abstract The aim of the study was to describe the distribution of pea root mass in the soil, over a three-year period, under varying weather conditions and at different levels of phosphorus application, by means of evaluating and comparing parameters of a mathematical model characterising cumulative root mass distribution. A two-factor experiment was conducted in Prusy, near Krakow: the first factor was the level of phosphorus application (0-70-140 kg P2O5 ha−1) and the second was the cultivars (six cultivars were tested). Experimental data produced using the model indicated that the root distribution was strongly differentiated by water availability in the years of the study. This appeared in some cases to be a more important factor than phosphorus application rates. The estimated soil depth at which 50% of the root mass was accumulated differed significantly for the dry and the wet year. In the wet year, only very high phosphorus application rates contributed to an increase in root mass distribution. The estimation of root mass distribution from the presented data can be used to improve phosphorus application depending on the amount of precipitation.

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Studies on phosphorus requirement of lentil and french bean intercropping with Indian mustard

The study was laidout during Rabi season of 1994-95 and 1995-96 at Student’s Instructional Farm, C.S. Azad University of Agriculture and Technology, Kanpur. The soil of experimental field was sandy loam, having low fertility status. Five cropping systems i.e., Indian mustard sole, Indian mustard + lentil, Indian mustard without lentil at same distance, Indian mustard + French bean and Indian mustard without French bean at same distance were tested under three levels of phosphorus (control, 30 kg P 2 O 5 /ha and 60 kg P 2 O 5 /ha). The highest yield of Indian mustard by 24.04 q/ha was harvested under treatment of Indian mustard sole. In associated cropping system of lentil and French bean, Indian mustard yielded by 11.72 q/ha and 15.52 q/ha seed yield, respectively. The yield of Indian mustard was obtained 16.95 q/ha at 30 kg P 2 O 5 /ha closely followed by 60 kg P 2 O 5 /ha (16.45 q/ha). The growth and yield traits of Indian mustard were concordant to the yields obtained from Indian mustard under different cropping systems and levels of phosphorus. The yield of intercropped lentil and French bean were harvested by 6.69 q/ha and 12.02 q/ha, respectively. Both inter crops provided more grain yield upto highest tested dose of 60 kg P 2 O 5 /ha closely followed by 80 kg P 2 O 5 /ha. The growth and yield attributes of both crops were commensurable to the yields obtained from lentil and French bean under cropping systems with Indian mustard and levels of phosphorus application.

Grain yield of common bean (Phaseolus vulgaris L.) varieties is markedly increased by rhizobial inoculation and phosphorus application in Ethiopia

A field experiment was conducted to assess plant growth, symbiotic performance and grain yield of common bean in response to rhizobial incoculation and phosphorus application at Galalicha in Southern Ethiopia during the 2012 and 2013 cropping seasons under rain-fed conditions. The treatments consisted of 2 released common bean varieties (Hawassa Dume and Ibbado), 3 levels of Rhizobium inoculation (uninoculated, inoculated with strain HB-429 or GT-9) and 4 levels of phosphorus application (0, 10, 20 and 30 kg P ha−1) using a split-split plot design with four replications. Here, phosphorus levels, Rhizobium inoculation and common bean varieties were assigned as main, sub- and sub-sub treatments, respectively. The results revealed marked varietal differences in plant growth, grain yield and symbiotic performance. Of the two common bean varieties studied, Hawassa Dume generally showed superior performance in most measured parameters in 2013. Rhizobium inoculation significantly (p ≤ 0.05) increased plant growth, symbiotic performance and grain yield. Applying Rhizobium strain HB-429 to bean crop respectively increased plant growth, %Ndfa, amount of N-fixed and grain yield by 19, 17, 54 and 48% over uninoculated control. Similarly, the application of 20 kg P ha−1 to bean plants respectively resulted in 36, 20, 96 and 143% increase in plant growth, %Ndfa, N-fixed and grain yield when compared to the control. These results clearly indicate that plant growth, symbiotic performance and grain yield of common bean can be significantly increased by Rhizobium inoculation and phosphorus fertilization in Ethiopia. Rhizobium inoculants are a cheaper source of nitrogen than chemical fertilizers and when combined with moderate phosphorus application can markedly increase grain yield for resource-poor farmers.

Studies on phosphorus requirement of lentil and French bean intercropping with Indian mustard

The study was laidout during Rabi season of 1994-95 and 1995-96 at Student’s instructional Farm, C.S. Azad university of Agriculture and technology, Kanpur. The soil of experimental field was sandy loam, having low fertility status. Five cropping systems i.e., Indian mustard sole, Indian mustard + lentil, Indian mustard without lentil at same distance, Indian mustard + French bean and Indian mustard without French bean at same distance were tested under three levels of phosphorus (control, 30 kg P 2 O 5 /ha and 60 kg P 2 O 5 /ha). the highest yield of Indian mustard by 24.04 q/ha was harvested under treatment of Indian mustard sole. In associated cropping system of lentil and French bean, Indian mustard yielded by 11.72 q/ha and 15.00 q/ha seed yield, respectively. The yield of Indian mustard was obtained 16.95 q/ha at 30 kg P 2 O 5 /ha closely followed by 60 kg P 2 O 5 /ha (16.45 q/ha). the growth and yield traits of Indian mustard were concordant to the yields obtained from Indian mustard under different cropping systems and levels of phosphorus. The yield of intercropped lentil and French bean were harvested by 6.69 q/ha and 12.02 q/ha, respectively. Both inter crops provided more granin yield upto highest tested dose of 60 kg P 2 O 5 /ha closely followed by 30 kg P 2 O 5 /ha. The growth and yield fruits of both crops were commensurable to the yields obtained from lentil and French bean under cropping systems with Indian mustard and levels of phosphorus application.

Arbuscular mycorrhiza effects on Faidherbia albida (Del.) A. Chev. growth under varying soil water and phosphorus levels in Northern Ethiopia

Tree seedling establishment, survival and growth in dryland areas is greatly impacted by water, land use effects and soil nutrient availability. Arbuscular mycorrhizal fungi (AMF) can have a substantial effect on water and nutrient uptake by seedlings and are affected by nutrient application, water availability and inoculum source. In this study, we examined the effect of AMF inoculation, phosphorus application levels, soil water status, and inoculum source on the growth of Faidherbia albida seedlings. Two greenhouse experiments were conducted on F. albida seedlings: to compare (a) ±AMF inoculation, at three levels of volumetric soil water content (field capacity (FC), 60% of FC and 20% of FC), and three AMF inoculum sources (derived from cultivated land, grazing land and area exclosure); (b) ±AMF inoculation, at four levels of phosphorus application (0, 25, 50 and 100 mg kg−1) and three AMF inoculum sources. Inoculation with AMF, higher soil water and higher P application significantly increased the growth of seedlings (P < 0.05). F. albida seedlings responded positively to increased water levels. The highest growth and AMF colonization of seedlings was recorded under the lowest water stress with AMF inoculum from area exclosure followed by grazing land inoculum source. The lowest growth was recorded under the highest water stress and cultivated land inoculum source. Plant growth and biomass were positively correlated with increased soil P application, however, AMF colonization decreased with increasing P application. Applying P and inoculating F. albida seedlings with indigenous AMF under low water stress enables optimum plant growth improvement in dryland farming systems.

Effect of phosphorus and sulphur on nutrient and amino acids content of soybean [Glycine max (L.) Merill] under ‘Eutrochrepts’

A field experiment was conducted at KVK, Srinagar during two consecutive kharif seasons of 2010 and 2011 to study the “Effect of phosphorus and sulphur on nutrient and amino acids content of soybean [Glycine max (L.) Merill] under Eutrochrepts”. The experiment was laid down under 16 treatment combinations viz four levels of phosphorus (0, 30, 60, 90 kg P2O5 ha-1) and four levels of sulphur (0, 15, 30, 45 kg S ha-1) in randomized complete block design with three replication . At higher levels of phosphorus application, Zn content of seed decreased and it was maximum at 30 kg P2O5 ha-1. With application of 45 kg S ha-1, N, P, K, Ca, Mg and S content in seed was 6.54, 0.555, 1.881, 0.329, 0.434 and 0.501 per cent respectively while as Zn, Fe, Cu, Mn was 109.99, 99.96, 2.82 and 3.73 mg kg-1, respectively. A significant interaction between P and S on macro as well as micronutrient content except Zn in seed was observed. Combined application of phosphorus and sulphur further enhanced the nutrient content of soybean seed. Combined application of phosphorus and sulphur enhanced the crude protein and oil content in soya seed 1. Individual as well as interaction effect of P and S was significant in enhancing the sulphur containing amino acids viz., cystine cystein and methionine content of soybean seed. Combined application of 45 kg S and 90 kg P2O5 ha-1 recorded significantly higher carbohydrate content (23.49%) in soybean seed. Application of increasing levels of phosphorus and sulphur resulted in gradual increase in linoleic (Omega-6) and linolenic acid (Omega-3).

Development and production response of edible and forage varieties of pea (Pisum sativum L.) to temporary soil drought under different levels of phosphorus application

The change in weather conditions in Central Europe has led to the need to review current standards for fertilization of pulse crops. Physiologists claim that phosphorus may play a significant role in raising tolerance to a temporary lack of water in the soil. The objective of the 2-year field study (2011–2012) was to assess the effect of phosphorus application on characteristics of the aerial and underground plant parts of different varieties of pea and elements of their yield structure. The study showed that a higher phosphorus application rate led to significant intensification of photosynthesis and thus to more rapid vegetative development in the plants, manifested as a greater number of leaves and greater leaf area. The higher rate of phosphorus application significantly influenced the flowering process of pea during soil drought. The number of flowering nodes increased significantly as phosphorus application increased. The plants fertilized with the higher level of phosphorus produced a greater weight of root nodules with more &lt;em&gt;Rhizobium&lt;/em&gt; bacterial colonies. Increased phosphorus fertilization had a significant role during the year of permanent semi-drought, 2012, resulting in a significantly greater number and weight of pods as well as a greater number and weight of seeds per plant, and thus a larger final yield.

Effect of Organic Substrate and Phosphorus Fertilization on Seed, Oil Yields and Composition of Medicinal Pumpkin (Cucurbita pepo var. Styriaca)

Intensive cropping systems with fertilizer responsive crops that rely on high input of inorganic fertilizers often lead to nonsustainability in production and also pose a serious threat to soil health. Application of organic sources of nutrients with no or very little use of fossil fuel-based inorganic fertilizers is rapidly gaining favor. However, considering economics and also physiological potential of varieties, entire dependence on organic sources of nutrients may not be adequate to attain the most productivity. Integrated nutrient management with both organic and inorganic fertilizers was investigated. A field trial was conducted with different fertilizer combinations of organic substrates (cow manure, spent mushroom substrates (SMS) and vermicomposts) and phosphorus fertilization (0, 75, 100 and 125 kg ha) to study their effects on seed number, seed phosphorus and zinc content, oil yield and oil quality in medicinal medicinal pumpkin seed (Cucurbita pepo var. styraca). For lonely application of organic substrates and phosphorus concentrations; vermicomposts and 125 P (kg.ha) treatments had the highest seed number, oil percentage with high value of oleic acid in medicinal medicinal pumpkin seeds. Results from the experiment revealed that among the sixteen treatments compared, the combination of vermicomposts and all levels of phosphorus applications had the maximum of seed number with high oil percentage and qualities. Perhaps in some combine vermicomposts and phosphorus fertilizer applications, linoleic decreased but because of effective role of these combinations on seed number and oil percentage, can help to increase the main important fatty acids.

Effect of Integrated Nutrient Management on Yield of Castor (Ricinus comunisL.) in Typic Ustochrept Soil of Hisar, Haryana

The present study was conducted for five rainy seasons (kharif) of 2005 to 2009 at a fixed site at the farm of AICRP for Dryland Agriculture, CCS Haryana Agricultural University, Hisar, India to study the effect of organic, inorganic and biofertilizer on seed yield of castor in Aridisols. The experiment consisted of nine treatments, each replicated thrice in a randomized block design. The treatments tried had significant effect on seed yield of castor over control except the treatment of application of 20 kg N/ha during all the five seasons. Conjunctive use of organic and biofertilizer with inorganic fertilizer application (20 kg N/ha) gave promising results when compared with 40 kg N/ha alone. This indicates the additive response to biofertilizers and organics (4 t FYM/ha). Increase in application of N40 from N60 to Ndid not affect the seed yield of castor significantly when compared with 40 kg N/ha at the same level of phosphorus application. The microbial count of Azotobacter and PSB was the highest at 30 and 60 days after sowing (DAS), respectively irrespective of treatments. Application of N60 P20 had recorded the highest benefit-cost ratio (BCR) of 1.58 closely followed by N40 P20 (1.54).

Profit Margin Analysis Of The Response Of Cowpea (&lt;i&gt;Vigna unguiculata&lt;/i&gt;) To Phosphorus Fertilizer And Poultry Manure In Ovonum, Obubra, Cross River State, Nigeria

Investigations were carried out to determine the growth, yield and profitability of cowpea (Vigna unguiculata), growth with different levels of phosphorus fertilizer and poultry manure. A randomised complete block design (RCBD) was used and the total treatments were four namely: 0.0kgP2O5/ha, 0.20kgP2O5/ha, 0.40kg P2O5/ha and Poultry droppings from broilers (10 tons/ha). The results showed that yield performance was better in manured than in control plots. Responses varied with different levels of phosphorus application in terms of yields. Effects of the phosphorus fertilizer (Single Super phosphate with 16 to 20 percent of P2O5 containing in addition, twelve percent (12%) of sulphur and more than twenty percent (20% ) of calcium [Ca ] were superior to organic manure (poultry droppings). The fresh weight of cowpea under the different manurial regimes were 5.25kg and 1.80kg for phosphorus and poultry droppings respectively. Comparatively, the profit margin (N61.88) for phosphorus fertilizer at 0.40kgp2o5/ha for year 2003 while in year 2004 the profit margin (N62.08) for phosphorus fertilizer at 0.40kgp2o5/ha .The profit margin for year 2004 was better than that of year 2003.A strong case is however made for poultry manure in this era of organic agriculture, where production is expected to be as close to nature as possible. Fertilising cowpea plots with poultry manure, would definitely help assuage the problem of the projected heavy tonnage of poultry waste as a result of increased poultry production. Poultry manure is an affordable option for the resource-poor farmer. Studies are however, on going to elucidate current fertilizer rates as well as develop optimum fertilizer formulae for intensive cowpea cultivation in the area. Effective extension services as well as efficient policy formulation, implementation, monitoring and evaluation by government are recommended. Keywords: Cowpea, profitability, phosphorus, organic fertilizer,Journal of Agriculture, Forestry and the Social Sciences Vol. 4 (2) 2006: pp. 40-49

Intensity of Ground Cover Crop Arachis pintoi, Rhizobium Inoculation and Phosphorus Application and Their Effects on Field Growth and Nutrient Status of Cocoa Plants

Arachis pintoiis potentially as a cover crop for cocoa (Theobroma cacaoL.) farm, however information regarding its effect on the growth of cocoa plants in the field is very limited. The objective of this experiment is to investigate the combined influence of ground cover crop A. pintoi, rhizobial bacterial inoculation and phosphorus (P) fertilizer on the growth of cocoa in the field and nutrient status. This experiment laid out in split-split plot design consisted of three levels of cover crop (without, A. pintoiand Calopogonium caeruleum), two levels of rhizobium inoculation (not inoculated and inoculated) and two levels of phosphorus application (no P added and P added). The results showed that in field condition the presence of A. pintoias cover crop did not affect the growth of cocoa. On the other hand, C. caeruleumas cover crop tended to restrict cocoa growth compared to A. pintoi. Application of P increased leaf number of cocoa plant. Biomass production of A. pintoiwas 40% higher than C. caeruleum. Soil organic carbon and nitrogen contents were not affected by ground cover crops, though higher value (0.235% N and 1.63% organic C) was obtained from combined treatments of inoculation and P addition or neither inoculation nor P addition. In the case of no rhizobium inoculation, soil N content in cocoa farm with A. pintoicover crop was lower than that of without cover crop or with C. caeruleum. Cover crop increased plant N content when there was no inoculation, on the other hand rhizobium inoculation decreased N content of cocoa tissue. Tissue P content of cocoa plant was not influenced by A. Pintoicover crop or by rhizobium inoculation, except that the P tissue content of cocoa was 28% higher when the cover crop was C. caeruleumand inoculated. Key words : Arachis pintoi, Theobroma cacao, Calopogonium caeruleum, rhizobium, nitrogen, phosphorus.

Copper release from chemical root-control baskets in hardwood tree production.

The City of Montreal, Canada, evaluated the environmental impact and usefulness of in-ground copper (Cu)-treated baskets in controlling root growth of hardwood trees in nursery culture. Using baskets planted with 5-yr-old Norway maple (Acer platanoides L.) trees, the amount and temporal pattern of Cu release from the basket surface into soil was determined for two copper formulations: Cu metal powder and Cu(OH)2. Release of both Cu formulations from the basket surface decreased exponentially over time, with Cu concentration at the basket surface dropping to 2% of the initial Cu applied by the end of the second field season. Total Cu content increased significantly in the soil around the baskets (from 7 to 28 mg Cu kg(-1) soil) and in the baskets (from 7 to 50-70 mg Cu kg(-1) soil) over the two years of the study. Three levels of phosphorus application (33, 66, and 100% of the regular nursery rate of 465 kg ha(-1) yr(-1)) did not affect release of Cu from the basket surface. The release of Cu metal at 28 and 105 d in the field was significantly increased by inoculation with the symbiotic arbuscular mycorrhizal fungus (AMF) Glomus intraradices Schenck & Smith; however, AMF inoculation had no affect on Cu(OH)2 release. Trees grown in Cu-treated baskets and inoculated with G. intraradices had similar colonization to non-inoculated trees, suggesting that inoculation was not very effective and that AMF inoculum was already present in the root ball of the trees at planting. After two years, copper basket-grown trees had significantly less root colonization than isolated control trees growing in the open field. This strongly suggests that conditions inside the baskets were not favorable to AMF.

Copper Release from Chemical Root-Control Baskets in Hardwood Tree Production

The City of Montreal, Canada, evaluated the environmental impact and usefulness of in-ground copper (Cu)-treated baskets in controlling root growth of hardwood trees in nursery culture. Using baskets planted with 5-yr-old Norway maple (Acer platanoides L.) trees, the amount and temporal pattern of Cu release from the basket surface into soil was determined for two copper formulations: Cu metal powder and Cu(OH)2 Release of both Cu formulations from the basket surface decreased exponentially over time, with Cu concentration at the basket surface dropping to 2% of the initial Cu applied by the end of the second field season. Total Cu content increased significantly in the soil around the baskets (from 7 to 28 mg Cu kg−1 soil) and in the baskets (from 7 to 50–70 mg Cu kg−1 soil) over the two years of the study. Three levels of phosphorus application (33, 66, and 100% of the regular nursery rate of 465 kg ha−1 yr−1) did not affect release of Cu from the basket surface. The release of Cu metal at 28 and 105 d in the field was significantly increased by inoculation with the symbiotic arbuscular mycorrhizal fungus (AMF) Glomus intraradices Schenck & Smith; however, AMF inoculation had no affect on Cu(OH)2 release. Trees grown in Cu-treated baskets and inoculated with G. intraradices had similar colonization to non-inoculated trees, suggesting that inoculation was not very effective and that AMF inoculum was already present in the root ball of the trees at planting. After two years, copper basket–grown trees had significantly less root colonization than isolated control trees growing in the open field. This strongly suggests that conditions inside the baskets were not favorable to AMF.

Rotation of maize with cowpea improves yield and nutrient use of maize compared to maize monocropping in an alfisol in the northern Guinea Savanna of Ghana

In the northern Guinea Savanna of Ghana (1984–1987) a field experiment was conducted to study the reasons for beneficial effects of rotating maize (Zea mays) and cowpea (Vigna unguiculata) on yield and N and P use of maize. The treatments included two cropping systems, maize monocropping and maize/cowpea rotation, two levels of nitrogen (0 and 80 kg N ha-1 as urea) and two levels of phosphorus application (0 and 60 kg ha-1 P as Volta phosphate rock). Yields and nutrient accumulation of maize were larger in rotation than in monocropping, independent of the N and P level. Fertilizer application (N and P) increased yields of maize in both cropping systems to the same extent. Nitrate contents of the soil after cowpea and after maize monoculture were comparable at the beginning of the cropping period. Also, potential nitrogen mineralization was only slightly larger after cowpea in the unfertilized plots. However, soil nitrate of fertilized plots was similar or even higher under monocropping than under crop rotation, especially in deeper soil layers and at the end of the cropping period. This indicates that in addition to the availability of mineral N, its use by the plants was limiting for the productivity of maize. Root length densities of maize were significant lower in monocropped maize than in maize grown in rotation. Soil physical parameters (infiltration, bulk density, aggregate stability and water capacity) showed a significant deterioration compared to a bush fallow plot, but differed only slightly between the cropping systems. Also in a pot experiment maize growth was much better in the soil from the crop rotation than from the monocropping plots, provided P was eliminated as the main growth-limiting factor. Since this effect persisted in spite of N application and optimization of soil physical properties by mixing the soil with polystyrol it is concluded that the results indicate that yield decline in maize monocropping might be due to allelopathic effects.

Early growth and N2-fixation of leucaena and gliricidia at different levels of phosphorus application

The phosphorus (P) uptake and use efficiency in relation to N2 fixation and growth of three provenances of gliricidia (Gliricidia sepium) two cultivars of leucaena (Leucaena leucocephala) and one ofL. diversifolia, all inoculated withRhizobium, were determined at five levels of P application. Increasing the P application rate resulted in a 33% increase in dry matter and total N ofL. diversifolia and an 18% dry matter increase of gliricidia provenance 13/84 over the control without P. Leucaena K8, which did not respond to P application, yielded as well with low P asL. diversifolia at the high P indicating the lower P requirement of cultivar K8. Leucaena cultivar Singapore did not yield well at either low or high P. Correlation analyses showed that differences between species and cultivars/provenances for P uptake per plant were largely related to differences in shoot growth rate and the distribution of P between roots and tops. P use efficiency was not related to dry-matter production. Genetic control of P and dry matter distribution of is probably more important than P availability in the growth media for gliricidia and leucaena provenances or cultivars. Increasing the P application rate significantly increased the number and mass of nodules in leucaena cultivars and gliricidia provenances. Significant increases in the proportion of N derived from atmospheric N2 (% Ndfa) due to low P application (20 mg P kg−1 soil) were observed within leucaena but not for gliricidia provenances. No significant increases in % Ndfa occurred with higher P application rates suggesting that symbiotic N2 fixationper se is stimulated only with low rates of P.