Comparative Performance of Geographical Isolates of Glomus mosseae in Field Crops under Low-Input Intensive P-Deficient Acid Alfisol

Comparative performance of five geographical isolates of Glomus mosseae screened from maize fields, soybean fields, vegetable fields, tea orchard, and citrus orchard was assessed in three major field crops (wheat, maize, and soybean) under low-input management in three glass-house pot experiments in a phosphorus (P)–deficient acid Alfisol. These geographical isolates of Glomus mosseae varied with respect to vesicular arbuscular mycorrhizal (VAM) spore count and root colonization in these crops with greatest spore count (240 per 250 g soil) and root colonization (28–34%) using previously screened local Glomus mosseae culture (VAM_L) of CSK Himachal Pradesh Agricultural University, Palampur, India, followed in order by VAM isolate from vegetable-based cropping system, Glomus mosseae isolate from soybean fields, and Glomus mosseae isolate from tea farm. Glomus mosseae isolate from vegetable-based cropping system remaining at par with local VAM culture (VAM_L), resulting in significantly greatest grain productivity in these field crops under low-input management. There was a considerable reduction in soil fertility with respect to NPK status over the control and initial status in pot soils inoculated with Glomus mosseae isolate from vegetable-based cropping system followed by local VAM strain (VAM_L), thereby indicating greater nutrient mobilization and productivity as well through this efficient Glomus mosseae strain in P-deficient acid Alfisol. In addition, Glomus mosseae isolates from different farming situations resulted in differential productivity and soil fertility under these field crops. Overall, Glomus mosseae isolate from vegetable-based cropping system proved its superiority in realizing greater productivity and nutrient mobilization compared to local Glomus mosseae VAM culture under low-input management in P-deficient acid Alfisol.     

Influence of Inorganic Phosphorus,VAM Fungi,and Irrigation Regimes on Crop Productivity and Phosphorus Transformations in Okra (Abelmoschus esculentus L.)–Pea (Pisum sativum L.) Cropping System in an Acid Alfisol

The present investigation was carried out at CSK Himachal Pradesh Agricultural University, Palampur, India, during 2009–2011 to economize inorganic phosphorus (P) and water needs of an okra (Abelmoschus esculentus)–pea (Pisum sativum) cropping system through vesicular arbuscular mycorrhizal (VAM) fungi (Glomus mosseae) in a Himalayan acid Alfisol. The field experiment was replicated three times in a randomized block design comprising 14 treatments consisting of 12 treatment combinations of two VAM levels [0 and 12 kg ha^?1], three phosphorus levels [50, 75, and 100% of recommended soil-test-based nitrogen (N)–P–potassium (K)], and two irrigation regimes [40 and 80% of available water-holding capacity of field soil (AWC)], in addition to one treatment with “generalized recommended NPK dose with generalized recommended irrigations (GRD)” and one treatment based on “farmers’ practice of plant nutrition and irrigation management in the region.” This article presents crop productivity and P dynamics studies during the second crop cycle of okra–pea sequence (2010–2011) and statuses of different P fractions in the soil after the second pea crop harvest during 2010–2011. Crop productivity and P uptake data in okra–pea sequence indicated that application of VAM + 75% P dose at either of two irrigation regimes did not differ significantly than GRD treatment and VAM + 100% P dose. It suggests an economy of about 25% inorganic P dose through VAM fungi. The treatments imbedded with VAM inoculation enhanced the P uptake in okra–pea system, on an average by 21% over the GRD and non-VAM-inoculated counterparts. Further, integrated application of P, VAM, and irrigation regimes evaluated in okra–pea sequence for 2 years led to greater status of water-soluble P (21%), sodium bicarbonate (NaHCO₃)–inorganic phosphorus (Pi) (11%), sodium hydroxide (NaOH)–Pi (9%), hydrochloric acid (HCl)–extractable–P (20%) over non-VAM-inoculated counterparts and low status of organic P (NaHCO₃-P_o and NaOH-P_o), all of which appreciably contributed to available P supply to plants in the present study in an acid Alfisol. The correlation coefficient reveals that contribution of inorganic P forms is highly correlated to crop productivity and total P uptake in okra and pea crops besides soil available P in the present study. Overall, it is concluded that VAM inoculation in okra–pea cropping system significantly enhanced the P availability to plants by way of enriching the labile-P pool such as water-soluble P and P loosely bound to aluminium (Al-P) and iron (Fe-P) on adsorption complexes and by P mineralization from organic matter in an Himalayan acid Alfisol.     

Distribution of Boron Forms in Relation to Soil Characteristics,Chemical Fertilizers,and Amendments in an Acid Alfisol of Northwestern Himalayas

Different forms of boron (B) were studied under long-term effect of chemical fertilizers and amendments in an acidic Alfisol of northwestern Himalayas. Residual B was dominant, comprising 71.5% of total B. Different B fractions correlated among themselves, showing interdependency of pools of B. On an average, all pools except for organically bound B exhibited depletion. Application of recommended doses of nitrogen (N), phosphorus (P), and potassium (K) with farmyard manure (FYM) in general showed less depletion in comparison to other treatments with the exception of liming treatment in oxide-bound B. Soil reaction (pH) had a significant positive relationship with most fractions. Except for residual and total B, significant positive relationships with other fractions of B with cation exchange capacity (CEC) were observed. Available B had a significant positive relationship with nonspecifically and specifically adsorbed B, indicating their importance in replenishing available B in soil. Imbalanced use of fertilizers had the most deleterious effects on soil properties.     

Enhancing Plant Water Relations,Quality, and Productivity of Pea (Pisum sativum L.) through Arbuscular Mycorrhizal Fungi,Inorganic Phosphorus,and Irrigation Regimes in an Himalayan Acid Alfisol

The present investigation was carried out at Palampur, India, during 2009–11 to enhance plant water relations and productivity in pea through arbuscular mycorrhizal fungi (AMF) in a Himalayan acidic Alfisol. The field experiment was replicated three times in a randomized block design comprising 14 treatments involving AMF, inorganic phosphorus (P), irrigation regimes, generalized recommended nitrogen, phosphorus, and potassium (NPK) dose and irrigations, and farmers’ practice in the region. The study revealed that treatments involving AMF inoculation along with inorganic P nutrition at varying irrigation regimes led to significantly greater relative leaf water content (2%), xylem water potential (12%), and water-use efficiency (10%), respectively, in comparison with non-AMF inoculated counterparts. Similarly, maximum increase in quality parameters such as total soluble solids (6%), ascorbic acid (6%), and crude protein content (3%) in pea was registered under AMF inoculation involving treatments. Further, AMF-inoculated treatments indicated an economy of about 25% in soil-test-based P dose without impairing crop productivity.     

中南地区淋溶土的层间羟基物矿物

将北纬 3 0°～ 3 2°亚热带花岗岩发育的两个淋溶土B层黏粒样分别用连二亚硫酸钠—柠檬酸钠—重碳酸钠 (DCB)溶液溶提处理和经DCB溶液处理后再用柠檬酸钠溶液溶提处理。从上述处理后样品的X射线衍射图谱中可看出 :供试土壤的膨胀性矿物层间有羟基物质 ,它们能被DCB溶液—柠檬酸钠溶液所溶解提取 ,含羟基物质的黏土矿物主要来源于蛭石 ,少量来自蒙皂石。DCB溶液—柠檬酸钠溶液处理前后黏粒红外差分光谱上显示的 980～ 970cm- 1 ,91 0～940cm- 1 吸收带 ,标志着供试土壤膨胀性矿物层间含有羟基铝硅酸和羟基铝离子。从而首次揭示了中国中南地区淋溶土的膨胀性矿物层间有羟基铝硅酸。     

Response of low-nitrogen tolerant maize genotypes to nitrogen application in a tropical Alfisol in northern Nigeria

In the dry savannas of west and central Africa, where low soil fertility is major constraint to maize production, the development of tropical maize genotypes with high and stable yield under low-nitrogen condition is very important, since access to these improved genotypes may be the only affordable alternative to many small scale farmers.

Field trials were conducted at Samaru (Typic Haplustalfs) to investigate the response of low-N tolerant maize cultivars to nitrogen (N) fertilizer. Nitrogen application rates were 0, 30, 60, 90 kg N ha⁻¹ and four maize cultivars (Low-N pool C2, ACR 8328 BN C7, Super Oba II and TZR-SR). Maize leaf area index, intercepted radiation, leaf area and stover weights were increased due to nitrogen application at flowering. For most of the parameters, 60 kg N ha⁻¹ appeared to have the significantly high values. However, there was no significant difference between application rates of 60 and 90 kg N ha⁻¹ in stem weight, stover weight, grain yield and shelling percent at harvest. Genotypic variation observed in the maize agronomic traits were not significant except in leaf weight and grain yield. The amount of nitrogen taken by maize increased with increase in fertilizer rates. Application of 30 and 90 kg N ha⁻¹ to soil increased the maize grain N concentration and total N uptake. About 45.3 kg ha⁻¹ and 8.8 g N kg⁻¹ nitrogen uptake was obtained in maize shoot and grain, respectively, at the application of 90 kg N ha⁻¹. Low-N pool C2 genotype had the highest grain N concentration and shoot uptake significantly higher than TZB-SR. Nitrogen fertilizer applied accounted for 97% variation in soil nitrate. There existed a positive and significant correlation between maize grain yield and leaf nitrogen uptake (r = 0.33, P < 0.01). Averagely, nitrogen fertilizer applied accounted for 86% variations in maize grain yield.     

Nitrogen dynamics and crop growth on an Alfisol and a Vertisol under a direct-seeded rainfed lowland rice-based system

Rice (Oryza sativa L.) followed by chickpea (Cicer arietinum L.) or a fallow is one of the predominant cropping systems in the rainfed lowlands of India. Crop rotation experiments over 3 years (1996–1998) to quantify N supply and demand under rainfed lowland rice–chickpea and rice–fallow cropping systems on a loam Alfisol and a clay Vertisol in Raipur, India were conducted under direct-seeded rice culture. The rice growth, yield, development and N accumulation were affected most by N rates (0, 40, 80, 120 kg ha⁻¹) followed by cropping system (rice–chickpea, rice–fallow) and soil types (Alfisol, Vertisol). The incorporation of chickpea in the cropping system helped in accumulating a greater amount of soil N than fallow. The rice yield, dry matter and N accumulated were significantly higher in rice–chickpea than rice–fallow systems on both soils and in all years. The lowest rice yields were recorded in 1997 due to unfavorable rainfall distribution. The total rainfall was the highest in this season, but most of it occurred during a short period at an early growth stage. The post-heading rains were lowest in this season and resulted in the lower rice yield as compared with that of 1996 and 1998. This indicates the significance of rainfall distribution in controlling yield in a rainfed environment. The rice yields were lower on Vertisol than Alfisol during periods of drought. The performance of chickpea was also better in Alfisol as compared with that in the Vertisol due to its better soil physical attributes. The residual effect of N applied to the preceding rice crop was non-significant on all yield, growth and N accumulation parameters of chickpea. The N balance computed from the top 70 cm soil layers indicated less N loss in the rice–chickpea system as compared with that in rice–fallow. The recovery efficiency at the highest N rate (120 kg N ha⁻¹) was higher for the rice–chickpea (57–61%) than that of rice–fallow (49–53%) system. The improved N balance for rice–chickpea system from third year onwards was due to switch to dry seeding and improved soil N status. The inclusion of legume and the effective capture of biologically fixed N and soil N through direct-seeded rice system in rainfed lowlands may help in improving the rice yield of resource poor farmers.     

Fractions of Manganese in Soil under Long-Term Experiment and Their Contribution to Manganese Availability and Uptake by Maize-Wheat Cropping Sequence

Manganese (Mn) is an essential micronutrient needed for plant growth and development, but it can be toxic to plants in excess amounts. Long-term fertilizer experiment and intensive cropping alter the soil properties and also affect its plant-available Mn contents. To understand the dynamics of Mn under long-term fertilizer experiment the present study was initiated during 1972 at the experimental farm of College of Agriculture, CSK HPKV, Palampur (32° 6′ N latitude and 76° 3′ E longitude) in a randomized block design with 11 treatments replicated three times with a maize-wheat cropping sequence. The soils of the experimental area in the beginning of the experiment were acidic in reaction and taxonomically classified as Typic Hapludalfs. Surface (0.0–20 cm) and subsurface (20–40 cm) soil samples taken after the harvest of maize (kharif, 2008) were analyzed for pools of Mn and chemical indices of soil quality using standard analytical methods. Besides, the pools of Mn were also determined in the composite soil samples drawn from adjacent fallow plots. Results showed that all the pools of Mn were noticeably greater in farmyard manure (FYM)–amended plots compared to zero-fertilized plots. Although the residual fraction was found to be the most dominant fraction, organically bound and exchangeable forms were found to play major roles in the nutrient supply, crop productivity, and nutrient uptake. The greatest productivity of maize (2008) and wheat (2008–09) was recorded under the 100% nitrogen, phosphorus, and potassium (NPK) + FYM treatment. FYM and lime treatments resulted in significantly greater uptake of all the nutrients by both the crops compared to other treatments. The organically bound fraction was found to have the greatest significant and positive correlation with yield and nutrient uptake of maize and wheat crops. Further regression analysis studies revealed that the organic form was the most important pool contributing towards the variation in the parameters. Exchangeable and organically bound forms contributed significantly towards diethylene triamine pentaacetic acid (DTPA)–extractable Mn.     

AM fungi lead to fertilizer phosphorus economy and enhanced system productivity and profitability in okra (Abelmoschus esculentus L.)–pea (Pisum sativum L.) cropping system in Himalayan acid Alfisol

The present investigation was carried out at CSK Himachal Pradesh Agricultural University, Palampur, Himachal Pradesh, India, during 2009–2011 to economize inorganic phosphorus (P) and enhance profitability of okra (Abelmoschus esculentus)–pea (Pisum sativum) cropping system through arbuscular mycorrhizal fungi (AMF). A field experiment was replicated thrice in a randomized block design comprising 14 treatments involving AMF (Glomus mosseae) at varying inorganic P (50%, 75%, and 100% of recommended soil test-based P dose) and irrigation regimes (40% and 80% available water capacity] in a Himalayan acid Alfisol. In okra, AMF inoculation at varying P and irrigation regimes registered higher P response ratio (PRR), net returns (10–18%), and benefit:cost (B:C) ratio (17–49%) compared to “generalized recommended P dose (GRD)” and their non-AMF counterparts. Similarly in pea, AMF inoculation at varying P and irrigation regimes again registered higher PRR, net returns (14–23%), and B:C ratio (10–58%) compared to GRD and non-AMF counterparts. Higher system productivity (7–16%) and profitability in terms of net returns (9–23%) and B:C ratio (10–54%) were also registered in AMF-imbedded treatments compared to non-AMF counterparts. Further, “AMF + 75% soil test-based P dose” at either of these irrigation regimes registered statistically similar okra–pea system productivity and profitability as that obtained under “100% soil test-based P dose” at either of two irrigation regimes, thus indicating an economy of soil test-based applied P dose by about 25%. Overall, the current study suggests that practice of AMF inoculation has great potential in enhancing system productivity and profitability besides cutting down about 25% inorganic P requirement in okra–pea production system in the Himalayan acid Alfisol.     

Nickel adsorption in two Oxisols and an Alfisol as affected by pH,nature of the electrolyte,and ionic strength of soil solution

Background, aim, and scope  The retention of potentially toxic metals in highly weathered soils can follow different pathways that variably affect their mobility and availability in the soil–water–plant system. This study aimed to evaluate the effects of pH, nature of electrolyte, and ionic strength of the solution on nickel (Ni) adsorption by two acric Oxisols and a less weathered Alfisol. Materials and methods  The effect of pH on Ni adsorption was evaluated in surface and subsurface samples from a clayey textured Anionic ‘Rhodic’ Acrudox (RA), a sandy-clayey textured Anionic ‘Xantic’ Acrudox (XA), and a heavy clayey textured Rhodic Kandiudalf (RK). All soil samples were equilibrated with the same concentration of Ni solution (5.0 mg L⁻¹) and two electrolyte solutions (CaCl₂ or NaCl) with different ionic strengths (IS) (1.0, 0.1 and 0.01 mol L⁻¹). The pH of each sample set varied from 3 to 10 in order to obtain sorption envelopes. Results and discussion  Ni adsorption increased as the pH increased, reaching its maximum of nearly pH 6. The adsorption was highest in Alfisol, followed by RA and XA. Competition between Ni²⁺ and Ca²⁺ was higher than that between Ni²⁺ and Na⁺ in all soil samples, as shown by the higher percentage of Ni adsorption at pH 5. At pH values below the intersection point of the three ionic strength curves (zero point of salt effect), Ni adsorption was generally higher in the more concentrated solution (highest IS), probably due to the neutralization of positive charges of soil colloids by Cl⁻ ions and consequent adsorption of Ni²⁺. Above this point, Ni adsorption was higher in the more diluted solution (lowest ionic strength), due to the higher negative potential at the colloid surfaces and the lower ionic competition for exchange sites in soil colloids. Conclusions  The effect of ionic strength was lower in the Oxisols than in the Alfisol. The main mechanism that controlled Ni adsorption in the soils was the ionic exchange, since the adsorption of ionic species varied according to the variation of pH values. The ionic competition revealed the importance of electrolyte composition and ionic strength on Ni adsorption in soils from the humid tropics. Recommendations and perspectives  The presence of NaCl or CaCl₂ in different ionic strengths affects the availability of heavy metals in contaminated soils. Therefore, the study of heavy metal dynamics in highly weathered soils must consider this behavior, especially in soils with large amounts of acric components.