Doses Of P2O5 Research Articles

Residue Mulch Effects on Potato Productivity and Irrigation and Nitrogen Economy in a Subtropical Environment

Depleting water resources in many regions of the world and increasing fertilizer nitrogen (N) cost necessitate efficient resource use. This is crucial in shallow-rooted crops like potato due to a great probability of water and N loss. In Indian Punjab, autumn potato experiences high temperature at planting time that causes poor growth and tuber yield. Mulching with crop residues provides favorable soil hydrothermal conditions that may enhance yield and economize irrigation and N use. This study examined the combined effects of residue mulch, irrigation, and N regimes on potato productivity in two soils in a subtropical environment of north-west India. Treatments included combinations of two mulch rates (0 and 6 t ha−1 rice residues) in main plots, three irrigation regimes (irrigation water to pan evaporation ratio of 2.0, 1.4, and 0.8 in the sandy loam and 2.0, 1.5, and 1.0 in the loamy sand) in subplots and four N rates (0, 135, 180, and 225 kg ha−1) in sub-subplots with three replications. Potato was planted in the second week of October with recommended doses of P2O5 and K2O and harvested in the last week of January. Tuber yield was higher in the sandy loam than in the loamy sand soil reflecting effects of available water capacity and inherent fertility. Mulching improved tuber yield by 22% on the sandy loam and by 31% on the loamy sand. Irrigation benefits were more in the sandy loam (20%) than in the loamy sand (14%). Nitrogen response was also greater in the sandy loam soil. Interactions between mulching and irrigation showed that yield gains from mulching were greater in less frequent irrigation regimes. For a given yield, mulching saved 90–100 mm of irrigation water. Mulching benefits were also greater at low N regimes, demonstrating a saving of 90 kg N ha−1 for a given yield. Mulching and N enhanced water productivity (WP), and these effects were greater in less frequent irrigations. Mulching effects on tuber yield, irrigation, and N economy are attributed to its effects on moderation of soil temperature and reduction in soil water evaporation.

Spatial vatiability of the dosage of P2O5 and K2O tofertilize in variable rate and in a conventional way in a coffee field

Fewer studies have been conducted on the spatial variability of inputs dosage in crop field, mainly when it has been performed the comparison between conventional management and precision agriculture management in coffee crop.The aim of this article was to characterize the structure and magnitude of the spatial distribution of soil chemical attributes, and the recommendation of fertilizer application on a coffee field, and map these variables in order to identify the spatial dependence of them. It was also aimed compare the recommendation of fertilize application based on conventional sampling method and based on grid sampling method to demonstrate the advantages of the use of this crop management.. This study was carried out at the Brejao farm in Tres Pontas, Minas Gerais state, Brazil. As data base were used phosphorus and potassium sampled conventionally and sampled in a 64 point squared grid. The soil sampling was sent to a soil lab to proceed the analyses of the amount of chemical attributes present in the soil, that allowed to proceed the recommendation of fertilizer application. The analysis of these data by geostatistics tools allowed characterize the spatial variability of phosphorus and potassium, as well as, the dose of P2O5 and K2O recommended by the grid sampling method which allowed creating maps of spatial distribution of these variables. It was possible to identify differences presented in the P2O5 and K20 doses based on the recommendations obtained by the conventional sampling method and by the grid sampling method to precision coffee culture.

Site-Specific Nutrient Management for Rainfed Maize in Western Mid-Hills of Nepal

On-farm experiment was conducted in eight farmers’ field, of Khasyoli village development committee (952 to 1415 masl), Nepal, from April to September, 2011 to address the major constraint (nutrient management) to maize production through site-specific nutrient management (SSNM) as this approach is popular among scientists. The experiment comprised three nutrient omission plots (0N, 0P, and 0K), an ample NPK plot, and a farmers’ fertilization practice (FFP) plot, arranged in randomized complete block design. Farmers planted open pollinated variety (Manakamana-3) and managed in their way. Field-specific NPK application rates were calculated by considering nutrient demand, indigenous NPK supply and recovery efficiency of fertilizers. Grain yield in FFP (2.32 Mg/ha) and 0N (1.79 Mg/ha) plots differed significantly from each other and rest of the treatments, but was statistically similar among 0P (3.18 Mg/ha), 0K (3.40 Mg/ha) and ample NPK (3.38 Mg/ha) plots. Post-harvest grain and stover analysis revealed that indigenous NPK supply (20-71 kg N, 19-68 kg P2O5 and 51-164 kg K2O/ha) of soil vary among the farmers’ field. Moreover, soil was poor in indigenous N supply (42 kg/ha), but rich in indigenous P2O5 (35 kg/ha) and K2O (90 kg/ha) supply, on an average. As per the principles of SSNM, the initial fertilizer recommendation made can vary from 40-222 kg N, 0- 93 kg P2O5, and 0-50 kg K2O/ha. On an average, farmers may apply no or lower dose of P2O5 (18 kg/ha) and K2O (3 kg/ha) but need to significantly increase dose of N (143 kg/ha) fertilizer for enhancing soil and maize productivity.Int J Appl Sci Biotechnol, Vol 3(2): 227-231 DOI: http://dx.doi.org/10.3126/ijasbt.v3i2.12538

Phosphorus fertilization and growth of buffel grass (Cenchrus ciliares L.) cultivars

Phosphorus (P) plays an important role in the growth of root system as well as the tillering grass, being fundamental to increase the productivity of these species. The aim of this study was to evaluate the development of buffel grass cultivars and establish critical values of P in plant and soil. The experimental set up was a 4 x 5 factorial scheme (four Cenchrus ciliaris cvs.: Biloela, Aridus, CPATSA 7754 and Pusa Giant, and five doses of P2O5 - 0, 30, 60, 90 and 120 kg ha-1) with four replications. After 90 days of cultivation, dry mass of shoot (DMS) and root (DMR) production and the P accumulation (Pacc) were determined. Soil samples to determine the P content and determination of the critical level (CriLev) were also collected. The cv. Biloela presented lower DMR and DMS production compared to the other cultivars. The cultivares Biloela, Pusa Giant and Aridus showed different critical levels of P in soil and plant, obtained in the greenhouse showing that they have different requirement of this nutrient for their growth. The cultivar CPATSA 7754 showed higher phosphorus requirement and did not permit to establish critical levels with doses used in the present study.

Doses de nitrogênio e fósforo para produção econômica de milho na Chapada do Apodi, RN

Este estudo foi realizado no município de Baraúna, RN, no ano agrícola de 2010, em um Cambissolo Háplico eutrófico e derivado de calcário objetivando definir a melhor combinação das doses de nitrogênio (N) e fósforo (P) associadas à máxima produção econômica de grãos de milho, assim como os níveis críticos de N na folha e de P no solo e na folha. Foram aplicados 17 tratamentos sendo 16 resultantes da combinação entre quatro doses de N (30, 60, 90 e 120 kg ha-1) e de quatro doses de P2O5 (30, 60, 90 e 120 kg ha-1) e um tratamento testemunha no qual não se aplicou nenhuma dose desses nutrientes. O delineamento experimental utilizado foi o de blocos ao acaso, com quatro repetições. A melhor combinação das doses de N e de P2O5 recomendadas para a produção de máxima eficiência econômica de grãos foi de 70 kg ha-1 de N combinado com 120 kg ha-1 de P2O5. Os níveis críticos de N na folha e de P no solo e na folha, associados à produção de máxima eficiência econômica de grãos de milho foram, respectivamente, de 32,93 g kg-1, de 7,97 mg dm-3 e de 3,11 g kg-1.

Adubação Fosfatada no Milho com Fertilizante Organomineral em Latossolo Vermelho Eutroférrico

This study aimed to assess the nutritional status, yield components and grain yield of corn hybrid 30F35 cultivated Oxisol in no-tillage for 12 years, located in Tupassi/PR, with different phosphate sources.The experimental design was a randomized block design with 10 treatments and four replications. Treatments were arranged in a 5 x 2 factorial consisting of 5 doses of phosphorus (P) (0, 30, 60, 90, 120 kg ha -1 P2O5) and two sources: Umostart (46% P2O5, microgranulate) and Monoammonium Phosphate (MAP) (48% P2O5), totaling 40 plots. At flowering was rated the content of N, P and K and the harvest was evaluated the components of production and yield. The fertilizer organomineral Umostart and MAP did not influence the levels of N and K in leaf tissue, as well as the production components spike length, number of kernel rows per ear and 1000 grain weight in corn for hybrid 30F35. Increasing doses of P2O5 increased just foliar P for both the P2O5 sources, reaching 2.49 g kg -1 on the dose of 120 kg ha -1 of P2O5. Sources Umostart and MAP provided the same yield of

Grain crops and forage yield resulting from the use of phosphates in integrated production system

The aim of this study was to assess the effects of the sources and levels of surface-applied (broadcast) phosphorus (P) when sowing the winter annual forages on phosphorus accumulation and yields of maize, soybean, black oat and annual ryegrass crops in a crop-livestock integration system over three years. The experiment was established in April 2009, in the municipality of Castro, Parana, Brazil. The treatments consisted of the broadcast application when sowing the winter forages of four doses (0, 60, 120 and 180 kg ha-1 year-1) of total P2O5 as triple superphosphate (TSP), rock phosphate (RP-Arad) and magnesium termophosphate (MTP). The dry matter yields of black oat (2009 and 2011), annual ryegrass (2010), maize (2009/10 and 2011/12) and soybean (2010/11) and the accumulation of P in these crops were assessed. TSP provided the highest yield of total dry matter (TDM) and P accumulation only for black oat in the first year of cultivation. In the second year, MTP resulted in higher P accumulation than occurred with the other P sources in annual ryegrass and soybean, and both MTP and TSP provided higher P accumulation and grain export. In the third year, MTP provided a higher TDM yield and P accumulation for both the black oat and maize crops, resulting in the greatest residual effect over time.

Utilization of Harvested Water for Protective Irrigation and Mulching with Integrated Nutrient Management to Mitigate Dryspell for Maize (Zea maysL.) Production under Dryland Conditions

In kharif, 2012 there was a drought condition in the eastern dry zone of Karnataka where the rainfall accounted for only about 59.5% of the normal rainfall. To assess the effect of protective irrigation and mulching to mitigate dryspell with integrated nutrient management in maize production, a field experiment was conducted at All India Co-ordinated Research Project for Dryland Agriculture, UAS, GKVK, Bangalore during kharif, 2012. The experiment was laid out in a split plot design and replicated thrice which consisted of three main treatments viz. M1 (no protective irrigation and no mulch); M2 (protective irrigation) and M3 (protective irrigation with weed biomass mulching), and three sub-treatments viz. N1 (recommended doses of fertilizers); N2 (50% N substituted through poultry manure) and N3 (50% N substituted through Glyricidia green leaf manuring) with recommended doses of P2O5 and K2O through fertilizers. Three protective irrigations of 246926 l/ha were given through harvested water collected in the farm pond. Significantly higher growth parameters, yield attributes, kernel yield (5424 kg/ha) and stover yield (10342 kg/ha) of maize was observed in the plots under protective irrigations and mulching. Among the nutrient management treatments, recommended dose of fertilizers gave significantly higher kernel (5628 kg/ha) and stover yield (9825 kg/ha).

Availability of phosphorus for maize in crop-livestock integration system

The objectives of this study were to assess the concentrations of available phosphorus (P) extracted using the Mehlich-1 (M1), ion exchange resin (IER) and modified Morgan (MM) methods after 36 months of experimentation with the application of phosphates in a crop-livestock integration system (CLIS). Moreover, this study aimed to assess which extraction method provides the best correlation of P concentrations with the maize crop attributes. The treatments consisted of applying annual doses of P2O5 on the soil surface of the total area during the sowing of winter forage crops in the form of triple superphosphate (TSP), rock phosphate (RP) or magnesium thermophosphate (MTP). After 36 months of experimentation, soil samples were collected from the 0-5, 5-10, 10-15 and 15-20 cm layers to assess the concentrations of available P. The dry matter yield (DMY), the grain yield (GY), the accumulation of phosphorus in the dry matter (P-DM) and the export of phosphorus (P-Ex) were quantified in maize. The IER method extracted greater amounts of available P, followed by the M1 and MM extractions. The treatments that included the application of TSP and either the M1 or IER extractions had similar efficacies when correlated with the DMY, GY, P-DM and P-Ex attributes of maize. The P extracted by the IER was most correlated with P-DM and P-Ex for the water-insoluble P sources (RP and MTP). The MM solution was ineffective at predicting the availability of P for maize grown in a soil with that had received varying doses and sources of P applications in a CLIS.

Glycine–Glomus–Phosphate Solubilizing Bacteria Interactions Lead to Fertilizer Phosphorus Economy in Soybean in a Himalayan Acid Alfisol

Effects of Glycine–Glomus–phosphate solubilizing bacteria (PSB) interactions were studied on productivity, nutrient dynamics, and root colonization in soybean in a phosphorus (P)–deficient Himalayan acidic Alfisol in a greenhouse experiment. Treatments consisted of three vesicular arbuscular mycorrhizae (VAM) cultures, VAML [VAM culture, Glomus mosseae, developed by CSK Himachal Pradesh Agricultural University, Palampur, India], VAMT [VAM culture, Glomus intraradices, developed by Centre for Mycorrhizal Research, The Energy and Resources Institute (TERI), New Delhi, India], and VAMI [VAM culture, Glomus mosseae, developed by Indian Agricultural Research Institute (IARI), New Delhi, India], and a local PSB culture (Pseudomonas striata) alone or in combination with or without 75% of recommended phosphorus pentoxide (P2O5) dose based on targeted yield concept following the soil-test crop response (STCR) precision model. Sole application of PSB or either of the above VAM cultures considerably enhanced VA-mycorrhizal root colonization and root weight besides crop productivity and nutrient uptake over control. A similar stimulatory effect with significant enhancement on mycorrhizal root colonization and root weight was observed with coinoculation of PSB and VAM cultures over the control. Dual inoculation of VAM and PSB cultures also resulted in significant improvement in grain and straw yield besides grain protein content, thereby revealing a synergistic interaction between VAM and PSB. Coinoculation with either of VAMT (Glomus intraradices) or VAMI (Glomus mosseae) + PSB + 75% P2O5 dose remained at par with sole application of 100% P2O5 dose with respect to crop productivity, nutrient content, nutrient uptake, and soil fertility status besides the greatest root colonization and root weight at flowering, indicating that Glycine–Glomus–PSB interactions in combination with 75% P2O5 dose based on STCR precision model lead to economization of fertilizer P by about one-fourth without impairing crop productivity and soil fertility in soybean in a Himalayan acidic Alfisol.

Effects of Vesicular Arbuscular Mycorrhizae and Applied Phosphorus through Targeted Yield Precision Model on Root Morphology, Productivity, and Nutrient Dynamics in Soybean in an Acid Alfisol

A field experiment was conducted in a phosphorus (P)–deficient acidic Alfisol in northwestern Himalayas to study the effect of three vesicular arbuscular mycorrhizae (VAM) cultures [VAML, local VAM culture (Glomus mosseae) developed by CSK Himachal Pradesh Agricultural University, Palampur, India; VAMT, VAM culture (Glomus intraradices) developed by Centre for Mycorrhizal Research, The Energy and Resources Institute (TERI), New Delhi, India; and VAMI, VAM culture (Glomus mosseae) developed by Indian Agricultural Research Institute (IARI), New Delhi, India] on growth, productivity, and nutrient dynamics in rainfed soybean. Plant height, aboveground dry matter, root dry matter, total dry matter, root length, root weight density, Rhizobium root nodule count, root colonization, yield attributes, yield, and nutrient uptake of soybean increased consistently and significantly with increase in inorganic P levels from 25 to 75% of recommended P2O5 dose based on targeted yield precision model coupled with various VAM cultures. VAMT (Glomus intraradices) at each P level showed its superiority over VAMI and VAML. Sole application of any of the three VAM cultures produced similar growth and development parameters as well as grain yield (18.68 to 19.08 q ha−1) as produced through farmers’ practice (nitrogen at 20 kg ha−1), indicating that VAM has a vital role in root morphology and nutrient dynamics in a soil–plant system, though significantly greater productivity was obtained with 100% of the recommended P2O5 dose based on soil-test crop response (STCR) precision model without VAM inoculation. Targeted grain yield of soybean (25 q ha−1) was achievable with 75% of the recommended P2O5 dose applied with any of the three VAM fungi cultures without impairing soil fertility, thereby indicating that VAM fungi can save about 25% P fertilizer in soybean in P-deficient acidic Alfisols of northwestern Himalayas.

Crescimento e produção de pinhão-manso (Jatropha curcas L.) sob doses de fósforo

O presente trabalho objetivou avaliar a influência da adubação fosfatada sobre o crescimento e produção do pinhão-manso (Jatropha curcas L.). Mudas de pinhão-manso, com dois meses de idade foram transplantadas no mês de fevereiro de 2007. No mês de junho de 2008 foi realizada poda drástica em todas as plantas na altura de 80 cm do solo. Os tratamentos foram constituídos pelas doses de P2O5: 0, 50, 100, 150 e 200 g cova-1.O delineamento experimental utilizado foi em blocos casualizados,com quatro repetições de oito plantas, totalizando 40 plantas por bloco. O período de avaliação do experimento compreendeu-se entre o mês de outubro de 2008 a outubro de 2009 (correspondente ao 2° ano de avaliação), e entre o mês de outubro de 2009 a outubro de 2010 (correspondente ao 3° ano de avaliação),sendo as variáveis avaliadas:o número de ramos antes da poda, o número de ramos após a poda,o número de ramos com inflorescência,o número de inflorescência planta-1,o número de ramos com cachos,o número de cachos planta-1 e aprodutividade. A poda estimulou o crescimento e produção do pinhão-manso. O incremento na adubação fosfatada elevou a produtividade de pinhão-manso, alcançando uma estabilidade a partir da dose de 150 g ha-1 de P2O5. A cultura de Pinhão-manso pode ser considerada uma espécie que responde à adubação fosfatada.

Effect of Vesicular Arbuscular–Mycorrhizal Fungi and Phosphorus Application through Soil-Test Crop Response Precision Model on Crop Productivity, Nutrient Dynamics, and Soil Fertility in Soybean–Wheat–Soybean Crop Sequence in an Acidic Alfisol

A field experiment was conducted in a phosphorus (P)–deficient acidic alfisol of the northwestern Himalayas using three vesicular arbuscular mycorrhizal (VAM) cultures: a local culture developed by CSK Himachal Pradesh Agricultural University, Palampur (Glomus mosseae), VAM culture from Indian Agricultural Research Institute (IARI), New Delhi (Glomus mosseae), and a culture from the Centre for Mycorrhizal Research, The Energy Research Institute (TERI), New Delhi (Glomus intraradices). These were applied alone or in combination with 25 to 75% of recommended P2O5 and recommended nitrogen (N) and potassium (K) based on soil-test crop response (STCR) precision model with an absolute control, farmers’ practice, and 100% of recommended P2O5 dose based on the STCR model. The results revealed that sole application of either of the three VAM cultures have produced 2.68 to 9.81% and 25.06 to 28.62% greater grain yield than the control in soybean and wheat crops, respectively. Besides greater straw yield, NPK uptake as well as soil nutrient buildup increased. Increase in P fertilization from 25 to 75% of recommended P2O5 dose coupled with VAM inoculation with either of the three VAM cultures resulted in consistent and significant improvement in crop productivity (grain and straw yields), NPK uptake, and improved soil nutrient status, though significantly greatest magnitude was obtained with sole application of 100% of the recommended P2O5 dose. The targeted grain yields of soybean (25 q ha−1) and wheat (30 q ha−1) were achievable with 75% of recommended P2O5 dose along with mycorrhizal biofertilizers, thereby indicating that application of efficient VAM fungi with 75% of recommended P2O5 dose can economize the STCR precision model fertilizer P dose by about 25% without impairing crop yield targets or soil fertility in a soybean-based cropping system in an acidic alfisol.

Fertilizer Economy through Vesicular Arbuscular Mycorrhizae Fungi under Soil-Test Crop Response Targeted Yield Model in Maize–Wheat–Maize Crop Sequence in Himalayan Acid Alfisol

The effect of three vesicular arbuscular mycorrhizae (VAM) cultures with or without inorganic phosphorus (P) was studied in a maize–wheat–maize crop sequence in a P-deficient acidic Alfisol. Application of these three VAM cultures (Glomus mosseae, developed by CSK Himachal Pradesh Agricultural University, Palampur; Glomus intraradices, developed by the Energy and Resources Institute, New Delhi; and Glomus mosseae, developed by the Indian Agricultural Research Institute, New Delhi) alone or with 25% to 75% of recommended P2O5 dose based on soil-test crop response (STCR) precision model along with 100% of recommended nitrogen (N) and potassium (K) caused significantly greater grain and straw yield, NPK uptake, and soil nutrient buildup over the control and also increased crop yield and NPK uptake consistently and significantly with increases in applied P from 25% to 75% P2O5 dose. Results implied that application of either of the three VAM cultures with 75% P2O5 dose can economize the yield-targeted fertilizer P dose to the extent of about one fourth of the P requirement in maize–wheat–maize crop sequence without impairing yield targets and soil fertility in a P-deficient acidic alfisol.

Componentes de produção de pinhão manso irrigado com água de diferentes condutividades elétrica e doses de fósforo

O pinhão manso tem atraído bastante interesse nos últimos anos por apresentar elevado potencial de fornecer óleo para produção de biocombustível e isso tem provocado a expansão rápida das áreas de cultivo em todo mundo. Este trabalho teve como objetivo avaliar a influência da irrigação com água de diferentes condutividades elétricas (CEa) e doses de fósforo sobre os componentes de produção de pinhão manso durante o terceiro ano de produção. Usou-se o delineamento em blocos casualizados em um fatorial (5x2) com quatro repetições, sendo cinco níveis de salinidade (CEa - 0,6 testemunha; 1,2; 1,8; 2,4 e 3,0dS m-1) da água de irrigação e duas doses de P2O5 (135 e 200g planta 1 ano-1), em que a água de 0,6dS m-1 refere-se à água de abastecimento e à dose de 135g planta-1, a recomendação para o pinhão manso. As plantas foram cultivadas em vasos com capacidade de 200L e irrigados a cada três dias. O número de dias para inflorescência, número de cachos planta-1, produtividade de sementes e o teor de óleo das sementes de pinhão manso foram afetados negativamente pelo o aumento da salinidade da água de irrigação. A cultura do pinhão manso irrigado com água com condutividade elétrica de 1,3dS m-1 reduz 10% da produtividade das sementes e consequentemente do teor de óleo em suas sementes. Somente o número de dias para inflorescência foi afetado pelas doses de fósforo. Verificou-se correlação positiva e significativa entre o peso de 100 sementes e o teor de óleo das sementes que, respectivamente, foram 90,26g e 36,39% no tratamento irrigado com a água de menor condutividade elétrica.

Phosphorus fertilization influences grain yield and oil content in crambe

Crambe (Crambe abssynica Hoechst) is an oilseed crop belonging to the Brassicaceae family, with high oil content, and thus a material for biodiesel production. This study was conducted in 2010 and 2011 at Umuarama County, State Parana, aiming to determine the effects of doses of phosphorus (0, 15, 30, 60 and 90kgha−1) on grain yield and oil content. A completely randomized block design with four replications was adopted. Increased doses of P2O5 resulted in higher grain yield but the seed oil content was not influenced.

Meat and Bone Meals in Agronomy Performance of Tifton Grass

A major problem is tropical pasture conditions in acid soils of low fertility. In this context the condition of nutrition of forage plants has low availability of phosphorus (P). The present study aimed to evaluate the effect of two phosphate sources (meat and bone meals and superphosphate) in dry matter production of Tifton (Cynodon dactylon L.). The experiment was conducted from March to July 2011, in the experimental farm of UNIR, Rolim de Moura, RO. The ex- periment was carried out in buckets of 10 kg of soil. Treatments were the addition of increasing doses of P2O5 (0, 100, 200 and 300 kg ha -1 ) plots with nitrogen fertilization (20 kg ha -1 ) in each section (30 days), there is still a witness (only N) and absolute control (no N and no P). The randomized blocks design was used with five replicates (3x2+2). Variable analysis, had different levels of production in relation to the cutting times can be attributed to the difference in solubility between the sources of P2O5 studied. In terms of response in four sections, the production levels of dry matter generated by the meat and bones proved effective in relation to single super phosphate, ranging from 94%, 66% and 78% compared with the doses 100, 200 and 300 kg ha -1 , respectively. The meat and bone meal produced satisfactory answers in relation to dry matter production of Tifton, compared to conventional fertilization.

Aplicação do fósforo e da irrigação na absorção e exportação de nutrientes pelo algodoeiro

Objetivou-se, com este trabalho, avaliar o efeito de doses de fósforo em cultivos de sequeiro e irrigado, sobre a biomassa seca da parte aérea, o conteúdo e a exportação de nutrientes e a produtividade do algodoeiro. O experimento foi conduzido em Neossolo Quartzarênico, na região Norte de Minas Gerais. O delineamento experimental foi o de blocos ao acaso com quatro repetições, num arranjo fatorial de duas doses de P2O5 x dois sistemas de cultivo. Dois tratamentos adicionais, sem aplicação do fósforo em cada sistema, completaram os seis tratamentos estudados. Avaliaram-se o acúmulo de biomassa seca, o conteúdo e a exportação de nutrientes e a produtividade do algodoeiro. Os níveis de fósforo estudados não influenciaram o acúmulo de biomassa seca de parte aérea. O suprimento de P aumentou a exportação de P, Ca, Mg, S e Mn no cultivo irrigado e de N, K e Fe independentemente do sistema de cultivo. A irrigação aumentou a biomassa seca de parte aérea aos 80 dias após a emergência, o conteúdo de N, P, K, Ca, Mg, S, Cu, Fe, Mn, Zn e B, bem como a exportação desses pela colheita. Houve incremento do número de capulhos por planta, do rendimento de fibra e da produtividade com a irrigação. O aumento de produtividade com a aplicação do P foi condicionado ao uso da irrigação.

Improving Phosphorus Use through Co-inoculation of Vesicular Arbuscular Mycorrhizal Fungi and Phosphate-Solubilizing Bacteria in Maize in an Acidic Alfisol

Performance of three vesicular arbuscular mycorrhizal (VAM) fungi cultures and a phosphate-solubilizing bacteria (PSB) culture alone or in combination with or without 75% of the recommended P2O5 dose based on soil-test crop response model was examined in maize in a phosphorus (P)-deficient acidic Alfisol in a glasshouse pot experiment. Sole application of VAM besides co-inoculation with PSB (Pseudomonas striata) and inorganic P stimulated mycorrhizal root colonization. Sole application of PSB, VAMT (Glomus intraradices), and VAMI (Glomus mosseae) as well as co-inoculation of VAM with PSB significantly improved crop productivity besides grain protein content, thus indicating a synergistic interaction between VAM and PSB. Application of VAMT or VAMI + PSB + 75% P2O5 remained at par with sole application of 100% P2O5 dose with regard to productivity, nutrient uptake, and soil fertility status (particularly P), thus indicating economization of fertilizer P to the tune of about 25% without compromising crop productivity and soil fertility in an acidic Alfisol.

Influence of Vesicular Arbuscular Mycorrhizal Fungi and Applied Phosphorus on Root Colonization in Wheat and Plant Nutrient Dynamics in a Phosphorus-Deficient Acid Alfisol of Western Himalayas

Vesicular arbuscular mycorrhizal (VAM) fungi symbiosis confers benefits directly to the host plant's growth and yield through acquisition of phosphorus and other macro- and micronutrients, especially from phosphorus (P)–deficient acidic soils. The inoculation of three VAM cultures [viz., local culture (Glomus mosseae), VAM culture from Indian Agricultural Research Institute (IARI), New Delhi (Glomus mosseae), and a culture from the Centre for Mycorrhizal Research, Energy Research Institute (TERI), New Delhi (Glomus intraradices)] along with P fertilization in wheat in a P-deficient acidic alfisol improved the root colonization by 16–24% while grain and straw yields increased by 12.6–15.7% and 13.4–15.4%, respectively, over the control. Uptake of nitrogen (N), P, potassium (K), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) was also improved with VAM inoculation over control, but the magnitude of uptake was significantly greater only in the cases of P, Fe, Zn, and Cu. Inoculation of wheat with three VAM cultures in combination with increasing inorganic P application from 50% to 75% of the recommended P2O5 dose to wheat through the targeted yield concept following the soil-test crop response (STCR) precision model resulted in consistent and significant improvement in grain and straw yield, macronutrient (NPK) uptake, and micronutrient (Fe, Mn, Zn, Cu) uptake in wheat though root colonization did not improve at P2O5 doses beyond 50% of the recommended dose. The VAM cultures alone or in combination with increasing P levels from 50% to 75% P2O5 dose resulted in reduction of diethylenetriaminepentaacetic acid (DTPA)–extractable micronutrient (Fe, Mn, Zn, Cu) contents in P-deficient acidic soil over the control and initial fertility status, although micronutrient contents were relatively greater in VAM-supplied plots alone or in combination with 50% to 75% P2O5 dose over sole application of 100% P2O5 dose, thereby indicating the positive role of VAM in nutrient mobilization and nutrient dynamics in the soil–plant system. There was significant improvement in available N and P status in soil with VAM inoculation coupled with increasing P levels upto 75% P2O5 dose, although the greatest P buildup was obtained with sole application of 100% P2O5 dose. The TERI VAM culture (Glomus intraradices) showed its superiority over the other two cultures (Glomus mosseae) in terms of crop yield and nutrient uptake in wheat though the differences were nonsignificant among the VAM cultures alone or at each P level. Overall, it was inferred that use of VA-mycorrhizal fungi is beneficial under low soil P or in low input (nutrient)–intensive agroecosystems.