Acid Alfisol Research Articles

Effect of a four-decade long application of fertilizers, farmyard manure and lime, on forms of soil acidity and their relationship with yield of wheat and maize in an acid Alfisol

ABSTRACTThe present investigation was undertaken in the on-going long-term fertilizer experiment initiated during 1972 at experimental farm of Department of Soil Science, Himachal Pradesh Agricultural University, Palampur, India. Continuous application of fertilizers either alone or in combination with farmyard manure (FYM)/lime affected different forms of soil acidity (total acidity, total potential acidity, pH dependent acidity, extractable acidity, exchangeable acidity, and non-exchangeable acidity) significantly, in surface and sub-surface layers. Continuous cropping with the application of lime and optimal doses of fertilizers decreased different forms of soil acidity at all the depths, significantly. Highest productivity of wheat and maize was recorded in 100% (nitrogen, phosphorus, potassium) NPK + FYM, which was at par with 100% NPK + lime. Different forms of soil acidity were found to be negatively correlated with wheat and maize yield. Grain and straw/stover yield of wheat and maize showed the highest negative correlation values with non-exchangeable acidity.

Vertical Distribution of Sulfur Fractions in a Continuously Fertilized Acid Alfisol Under Maize​–Wheat Cropping System

ABSTRACTVertical distribution of sulfur fractions was studied in a long-term fertilizer experiment at the experimental farm of Department of Soil Science, Himachal Pradesh Agricultural University, Palampur (India), comprising various combinations of fertilizer and amendments. Initially, available nitrogen (N) was high, and phosphorus (P), potassium (K), organic carbon were optimum. Different forms, viz., available, water-soluble, heat-soluble, organic, and total sulfur were significantly affected by continuous cropping and decreased with depth. However at surface layer, 100% NPK(-S) resulted in 67%, 70%, 34%, 47%, and 48% reduction in these fractions, respectively, as compared to 100% NPK. Among all, organic sulfur was recorded highest. Hundred percent NPK + farmyard manure (at par with 100% NPK + lime) recorded highest maize and wheat yield. Hundred percent NPK(-S) recorded 39% and 44% reduction in grain yield of maize and wheat as compared to 100% NPK, respectively. Sulfur fractions were positively and significantly correlated with yield of maize​–wheat which shows the importance of sulfur fertilization.

Acidic leaching of potentially toxic metals cadmium, cobalt, chromium, copper, nickel, lead, and zinc from two Zn smelting slag materials incubated in an acidic soil

A column leaching study, coupled with acid deposition simulation, was conducted to investigate the leaching of potentially toxic metals (PTM) from zinc smelting slag materials (SSM) after being incubated in an acid Alfisol for 120 days at room temperature. Two SSMs (SSM-A: acidic, 10 yrs exposure with moderate high PTM concentrations versus SSM-B: alkaline, 2 yrs exposure with extremely high PTM concentrations), were used for the incubation at 0.5, 1, 2.5, 5 wt% amendment ratios in triplicate. Five leaching events were conducted at day 1, 3, 7, 14, and 28, and the leaching of PTMs mainly occurred in the first three leaching events, with the highest PTM concentrations in leachate measured from 5 wt% SSM amendments. After leaching, 2.5, 12, 5.5, 14, 11, and 9 wt% of M3 extractable Pb, Zn, Cd, Co, Cr, and Ni could be released from 5 wt% SSM-A amended soils, being respectively 25, 12, 4, 2, 2, and 2 times more than those from 5 wt% SSM-B amended soils. In the leachates, the concentrations of PTMs were mostly affected by leachant pH and were closely correlated to the concentrations of Fe, Al, Ca, Mg and P with Cd, Pb, and Zn showing the most environmental concern. Visual MINTEQ 3.1 modeling suggested metallic ions and sulfate forms as the common chemical species of PTMs in the leachates; whereas, organic bound species showed importance for Cd, Pb, Cu, and Ni, and CdCl+ was observed for Cd. Aluminum hydroxy, phosphate, and sulfate minerals prevailed as the saturated minerals, followed by chloropyromorphite (Pb5(PO4)3Cl) and plumbogummite (PbAl3(PO4)2(OH)5·H2O) in the leachates. This study suggested that incubation of SSMs in acidic soil for a long term can enhance the release of PTMs as the forms of metallic ions and sulfate when subjected to acid deposition leaching.

Mycorrhizal diversity of stevia (Stevia rebaudiana Bertoni) rhizosphere in Tawangmangu, Indonesia

Mycorrhizal fungi is a group of soil fungi with mutualistic symbiosis between fungi and plant roots. The diversity on mycorrhiza contributes the maintenance of plant biodiversity, ecosystem function, and plant productivity. Climate change may affects the distribution and diversity of mycorrhizal fungi, and thus the study on mycorrhizal diversity is important to develop the information about mycorrhizal function and utilization. The present study investigated mycorrhizal diversity in the rhizosphere of stevia at four locations in different altitudes and soil types. The samples taken from Tlogodlingo (Andisols 1), Kalisoro (Andisols 2), Nglurah (Alfisols 1) and Ledoksari (Alfisols 2) in Tawangmangu, Karanganyar, Central Java, Indonesia. The result showed that Glomus sp. and Acaulospora sp. were the common genus found at all locations, whereas Gigaspora sp. was the only species found in the acidic Alfisol soil. Statistical analysis indicated that altitude, soil pH, and P availability significantly positively correlated with mycorrhizal spore density. The increase of altitude, soil pH and P availability, also increase the mycorrhizal spore density. Mycorrhizal infectivity negatively correlated with C/N ratio.

Depth dynamics of soil N contents and natural abundances of 15N after 43 years of long-term fertilization and liming in sub-tropical Alfisol

ABSTRACTThe aim of this study was to understand impacts of long-term (43 years) fertilization on soil aggregation, N accumulation rates and δ15N in surface and deep layers in an Alfisol. Soil samples from seven treatments were analysed for N stocks, aggregate-associated N in 0–30 cm and the changes in δ15N in 0–90 cm depths. The treatments were: unfertilized control (control); recommended N dose (N); recommended N and phosphorus doses (NP); recommended N, P and potassium doses (NPK); 150% of recommended N, P and K doses (150% NPK); NPK + 10 Mg FYM ha−1 (NPK + FYM) and NPK + 0.4 Mg lime ha−1 (NPK + L). Results revealed that plots under NPK + FYM had ~39% higher total N concentrations than NPK + L in 0–30 cm soil layers. In NPK + L, macro-aggregates had 35 and 11% and microaggregates had 20 and 9% lower δ15N values than NPK + FYM in 0–15 and 15–30 cm soil layers, respectively. However, plots receiving NPK + FYM had ~39% greater deep soil (30–90 cm) N accumulation than NPK + L. These results would help understanding N supplying capacity by long-term fertilization and assist devising N management strategies in sub-tropical acidic Alfisols.

Effect of AM fungi and phosphorus fertilization on P-use efficiency, nutrient acquisition and root morphology in pea (Pisum sativum L.) in an acid Alfisol

ABSTRACTPhosphorus (P) availability to plants is a major constraint in acid soils. A study was conducted to determine the effect of arbuscular mycorrhizal fungi (AMF) under varying inorganic P and irrigation regimes on P availability and P-use efficiency in garden pea (Pisum sativum L.) in a Himalayan acid Alfisol. The experiment comprised of 14 treatments replicated thrice in a randomized block design. The results revealed that integrated use of AM fungi and inorganic P at either of the two irrigation regimes (IW/CPE0.6 or IW/CPE1.0) enhanced the green pea pod weight, green pod productivity and agronomic efficiency of applied P to the extent of 8.4%, 7.2% and 30.7%, respectively, over non-AMF counterparts as well as “generalized recommended NPK dose and irrigations (GRD).” AMF inoculation also led to enhanced nitrogen (N), P and potassium (K) acquisition (uptake) by 16.3%, 18.2% and 6% over non-AMF counterpart treatments. Further, AMF inoculation at varying P and irrigation regimes sharply enhanced the rooting depth (21.4%), root volume (23.5%), root dry weight (14.9%), root weight density (13.7%) as well as N concentration in root nodules (3.4%) over non-AMF counterparts and GRD practice. AMF also enhanced the mycorrhizal root colonization by 3.2 folds at flowering stage in AMF inoculated pea plants. AMF-imbedded treatments did not alter the available soil nutrient status (macronutrients and micronutrients) significantly in comparison to non-AMF counterparts in pea, available P status, however, increased to the extent of 6.5% over initial status. Further, AMF imbedded plots showed a slight build-up in soil organic carbon with nominal decrease in soil bulk density. AMF inoculation in pea also led to fertilizer P economy by about 25% soil-test-based P dose. Overall, AMF holds great potential in enhancing nutrient acquisition especially P besides influencing root morphology in order to harness better crop yields vis-à-vis fertilizer P economy by about 25% soil-test-based P dose in Himalayan acid Alfisol.

Long-term effect of inorganic fertilizers and amendments on productivity and root dynamics under maize-wheat intensive cropping in an acid Alfisol

Study on the soil nutrient status and crop productivity under continuous use of inorganic fertilizers and amendments in an acid Alfisol after 36 years (1972-73 to 2008-09) was carried out at Palampur, HP. Results showed that application of Recommended Dose of Fertilizer (120:60:40 kg/ha to maize and 120:60:30 kg/ha to wheat) with 10 t farmyard manure/ha applied once a year for 36 years resulted in 786 and 515 per cent increase in maize and wheat yields, respectively over control. Soil acidity rose from 5.8 to 4.58 with the application of fertilizers over 36 years. Conjoint use of FYM with 100 per cent NPK substantially improved the Organic Carbon status by 4.95 g/kg as well as available P, K and S by 154.1, 14.5 and 12.5 kg/ha, respectively in soil over its initial values, thereby indicating significant contribution towards sustaining the soil health. On the other hand, there was a drastic decline in the available N status of soil in all the treatments as compared to the initial value. The various root parameters viz., root mass density (4.08 kg m-3), root volume density (10.84 m3 m-3x10-3), root length density (2.60 m m-3 x 10-4), root surface area (204.12 m2 x 10-4) and root cation exchange capacity (8.37 c mol (p+) kg-1) were found to be highest in the plots with the application of 100% NPK + FYM. Thus, balanced use of fertilizers continuously either alone or in combination with amendments is necessary for sustaining soil fertility and productivity of crops.

Impact of biosolid application rates on competitive sorption and distribution coefficients of Cd, Cu, Ni, Pb, and Zn in an Alfisol and an Entisol

Abstract We investigated the effect of biosolid application rates (0 (control), 20 (BS1), 50 (BS2), and 100 Mg ha−1 (BS3)) on competitive sorption and distribution coefficients (Kd) of Cd, Cu, Ni, Pb, and Zn in an acidic Alfisol and in an alkaline Entisol originating from Greece. Sorption of all metals was stronger in the Entisol than that in the Alfisol. Lead showed the highest Kd followed by Cu, Cd, Zn, and Ni in both soils. Sorption of Cd, Cu, Ni, Pb, and Zn increased significantly with increasing biosolid application rate in the Alfisol. Although sorption of Cd, Ni, Pb and Zn in the Entisol incremented significantly, sorption of Cu decreased significantly with increasing the biosolid application rate compared to control. Sorption of Cd, Cu, Ni, Pb, and Zn enhanced with raising the added metal concentrations under the three rates (BS1, BS2, and BS3) in both soils. The impact of biosolid rates on metal sorption was more pronounced in the Alfisol than in the Entisol. Lead and Cu were more affected by biosolid than Cd, Zn, and Ni in both soils. This study shows that biosolid application enhanced sorption of the studied metals in the Alfisol at the three rates, while it enhanced Cd, Ni, Pb, and Zn sorption in the Entisol at high rates, thereby decreasing their mobilization. However, application of biosolid to the Entisol at the three rates decreased Cu sorption and thus might increase its mobilization.

Long-Term Effect of Fertilizers and Amendments on Depth-Wise Distribution of Available NPK, Micronutrient Cations, Productivity, and NPK Uptake by Maize-Wheat System in an Acid Alfisol of NorthWestern Himalayas

ABSTRACTThe present study was undertaken in the ongoing long-term fertilizer experiment initiated during 1972 at experimental farm of Department of Soil Science, Himachal Pradesh Agricultural University, Palampur (India). Soil samples collected from three depths (0–0.15, 0.15–0.30, and 0.30–0.45 m) were analyzed for pH; organic carbon; CEC; available N, P, and K; and micronutrients cations. Continuous use of optimal dose of fertilizers and FYM-influenced pH, organic carbon, CEC, available NPK, and DTPA extractable micronutrient cations significantly. The contents of organic carbon, available N, P, K, Fe, Mn, Zn, and Cu were higher in top soil layer (0–0.15 m) compared to lower depths (0.15–0.30 and 0.30–0.45 m). Highest productivity of wheat (89.89 q ha−1) and maize (156.52 q ha−1) was recorded under 100% NPK + FYM, which was at par with 100% NPK + lime. Application of 100% NPK along with amendments (FYM/lime) recorded significantly higher NPK uptake over other treatments.

Influence of vermicompost and split applied nitrogen on growth, yield, nutrient uptake and soil fertility in pole type frenchbean (Phaseolus vulgaris L.) in an Acid Alfisol

A field experiment was conducted for two years at Himachal Pradesh Agricultural University, Palampur on the influence of vermicompost and split applied nitrogen in pole French bean. Twelve treatment combinations comprising of organic manures, nitrogen fertilization and methods of application were evaluated. The performance of yield and yield related traits increased significantly with application of vermicompost, 125% of recommended nitrogen through split application. Use of vermicompost + 125% nitrogen resulted in highest seed yield (10.43 q/ha) and NPK uptake. Seed yield and NPK uptake with application of vermicompost + 75% N was at par with that of recommended application of N indicating thereby saving of 25% of nitrogen fertilizers. Split applied nitrogen at 125% of recommended dose resulted in 50% increase in seed yield over basal application. Hence, application of vermicompost and split applied nitrogen is a better option to harness high seed productivity and to maintain soil fertility.

Effect of Continuous Application of Fertilizers, Farmyard Manure and Lime on Soil Fertility and Productivity of the Maize-Wheat System in an Acid Alfisol

ABSTRACTA study on the long-term effect of fertilizers and amendments on crop productivity and changes in soil fertility in maize-wheat cropping system in an acid Alfisol was carried out in randomized block design (RBD) with 11 treatments. Continuous application of chemical fertilizers along with farmyard manure (FYM) or lime significantly influenced the grain and straw/stover yield and the uptake of nutrients by wheat and maize crops significantly. The organic carbon content increased from 7.9 to 12.1 g kg−1, cation exchange capacity (CEC) from 12.1 to 14.6 cmol (p+) kg−1 and available phosphorus from 21.9 to 75.2 kg ha−1 through the integrated use of organic and fertilizers for the last 42 years while the status of available nitrogen (N) and potassium (K) declined over the years in all the treatments. Continuous application of urea alone resulted in a drastic decline in soil pH at both depths. Imbalanced use of fertilizers led to a significant reduction in the productivity of both crops and depleted the soil fertility.

Agronomic bio-fortification and quality enhancement in okra–pea cropping system through arbuscular mycorrhizal fungi at varying phosphorus and irrigation regimes in Himalayan acid alfisol

ABSTRACTA field experimentation was conducted during 2009-2011 at CSK Himachal Pradesh Agricultural University, Palampur, India characterized with wet-temperate climate and acid Alfisol soil having medium available phosphorus content. The study aimed at bio-fortification and quality enhancement of okra (Abelmoschus esculentus)–pea (Pisum sativum) cropping system through arbuscular mycorrhizal fungi (AMF) (Glomus mosseae) at varying inorganic phosphorus (50, 75, and 100% soil-test-based recommended P dose) and irrigation regimes (40 and 80% available water capacity) in a Himalayan acid Alfisol. The results revealed that AMF and inorganic P significantly enhanced the concentrations and uptake of various primary [nitrogen (N), phosphorus (P), and potassium (K)]; secondary [calcium (Ca)]; and micronutrients [iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), boron (B), and molybdenum (Mo)] in okra and pea crops. However, effects of varying irrigation regimes were found to be nominal. In okra, AMF inoculation considerably enhanced N, P, K, B, and Mo uptake by 5, 19, 3, 4, and 15%, respectively, over their non-AMF counterparts. Likewise in pea, a higher amount of N (10%), P (26%), K (7%), Fe (7%), Cu (38%), Zn (20%), Mn (4%), B (7%), and Mo (13%) uptake was registered through AMF inoculation over their non-AMF counterparts. Application of soil-test-based P dose from 50% to 100% P also resulted in significant and consistent improvement in N, P, K, B, and Mo uptake both in okra and pea and in Zn, Cu, Mn, and Fe uptake in pea crop. Magnitude of increase in Ca content was to the tune of 13 and 4%, respectively, in okra fruits and pea pods following AMF inoculation, whereas crude protein content enhanced by 4% each in both the crops. Overall, the current study demonstrates the important role of AMF in nutrient enrichment and quality enhancement of okra and pea crops in acid Alfisol, besides considerable reduction in investment on chemical fertilizers. Results of current study suggest that AMF use in Himalayan production systems is of tremendous significance to harvest nutritionally-rich farm produce for Himalayan communities suffering from malnutrition especially anemia and Zn deficiency, and equally to resource-poor Himalayan farmers who ill-afford expensive external inputs.

Long-term Effect of Integrated Nutrient Management on Chemical and Microbial Properties of Soil under Rice (Oryza sativa L.)-Wheat (Triticum aestivum L.) System in an Acid Alfisol

Long-term Effect of Integrated Nutrient Management on Chemical and Microbial Properties of Soil under Rice (Oryza sativa L.)-Wheat (Triticum aestivum L.) System in an Acid Alfisol

Effect of Prescription-based Fertilizer Application on Different Fractions of Phosphorus under Wheat in an Acid Alfisol

Effect of Prescription-based Fertilizer Application on Different Fractions of Phosphorus under Wheat in an Acid Alfisol

Tripartite symbiosis of Pisum–Glomus–Rhizobium leads to enhanced productivity, nitrogen and phosphorus economy, quality, and biofortification in garden pea in a Himalayan acid Alfisol

ABSTRACTThe present study was carried out to assess nitrogen (N) and phosphorus (P) economy, quality, and productivity of garden pea (Pisum sativum L.) through dual-inoculation of arbuscular mycorrhizal fungi (AMF) and Rhizobium in an acid Alfisol. Experiment was laid out in randomized block design replicated thrice comprising 13 treatments viz. Rhizobium along with three graded N levels (25%, 50%, and 75% soil-test-based recommended N), AMF along with three graded P levels (25%, 50%, and 75% soil-test-based recommended P), dual-inoculation of AMF and Rhizobium conjoint with four graded N and P levels (25%, 50%, 75%, and 100% soil-test-based recommended N and P), and three other treatments viz. generalized recommended NP potassium (K) dose (GRD), farmers' practice, and absolute control. The results revealed that dual-inoculation of AMF and Rhizobium enhanced the pea productivity, macronutrient (NPK) and micronutrient iron, copper, zinc, and manganese (Fe, Cu, Zn, and Mn) concentrations, and their uptake besides enhancing garden pea quality. Also, dual-inoculation of both symbionts at 75% and 100% soil-test-based N and P dose behaved statistically alike with respect to pea pod yield, NPK uptake, and quality parameters like total soluble solids (TSS) and crude protein (CP), thus indicating an economy of about 25% soil-test-based N and P dose through co-inoculation. AMF and Rhizobium dual-inoculated treatments led to enhanced TSS and CP in pea pods by 4.2% and 6.2%, respectively, over GRD, while sole application of AMF- or Rhizobium-imbedded treatments could enhance these quality parameters by 2.1% only in each case. Similarly, the highest N and P response ratio was registered in dual-inoculated treatments. Overall, dual-inoculation of AMF and Rhizobium with 75% soil-test-based N and P dose in pea can save up to 25% fertilizer N and P dose in acid Alfisol.Also, this tripartite symbiosis besides enhancing pea quality led to better bio-fortified pea seeds with micronutrients especially Fe and Zn, which can greatly curtail the widespread anemia and Zn deficiency in humans living in Himalayan acid Alfisol.

Influence of rhizobium inoculation, split nitrogen application and plantgeometry on productivity of garden pea (Pisum sativum L.) in an acid alfisol

A field experiment comprising of twelve treatment combinations was conducted for two years at Himachal Pradesh Agricultural University, Palampur, India. Crop geometry treatment comprising of two row spacings (60 cm × 10 cm and 45 cm × 10 cm) were allocated to the main plots and six nitrogen management practices namely, Rhizobium inoculation in conjunction with 75 and 50 per cent of recommended N either as basal or split application and recommended N (100 %) were assigned in sub-plots. Wider spacing resulted in significant higher seed yield (7.3%) over close spacing along with superior performance of component traits and nutrient uptake. The split applied nitrogen resulted in better performance of different parameters which together enhanced seed yield by 13.8 per cent over recommended N as basal application. Augmentation of nitrogen with Rhizobium culture positively improved growth and yield parameters leading to net saving of 25 per cent N fertilizers as evident from higher seed yield in treatment comprising 75 per cent split applied N + Rhizobium over recommended N. Interaction effects of split applied N at both row spacings resulted in better performance for seed yield, other related traits and uptake of NPK. Split applied 100 per cent N at wide spacing resulted in 15.5 and 23.6 per cent higher seed yield over recommended N at wider and close spacing, respectively. It could be concluded that Rhizobium inoculation could save 25per cent synthetic fertilizer N. Wider spacing (60 cm × 10 cm) and split applied nitrogen was a better preposition for enhancing productivity of pea in an acid alfisol under north western Himalayas.

Effect of Mycorrhiza, Organic Sources, Lime, Secondary and Micro-nutrients on Soil Microbial Activities and Yield Performance of Yam Bean (Pachyrhizus erosus L.) in Alfisols

ABSTRACTEffect of integrated use of mycorrhiza, lime, inorganic fertilizers, and organic manures on microbial activities and yield performance of yam bean (Pachyrhizus erosus L.) was studied for two consecutive kharif (rainy) seasons during 2013–14 and 2014–15 in an acid Alfisol. The experiment was laid out with 16 treatments consisting of graded doses of soil test–based nitrogen, phosphors, and potassium (NPK); lime; mycorrhiza; organic sources, that is, farmyard manure (FYM), vermicompost, and green manure; secondary magnesium sulfate (MgSO4) and micronutrients zinc sulfate (ZnSO4 and borax). Significantly highest mean tuber yield (29.61 t ha−1) was recorded due to integrated application of lime + FYM + NPK + ZnSO4. Graded doses of NPK showed a mean yield response of 65%, 134%, and 191% due to addition of 50%, 100%, and 150% of NPK over control, respectively. Inoculation of vesicular–arbuscular mycorrhiza (VAM) combined with NPK and FYM recorded a mean tuber yield of 25.14 t ha−1. Highest mean dry matter (18.85%) was recorded due to application of 150% NPK, whereas highest starch content on fresh weight basis was recorded due to integrated use of lime + FYM + NPK + MgSO4 (11.11%). Application of 150% NPK has recorded highest dehydrogenase activity (2.018 µg TPF h−1 g−1) and fluorescein diacetate hydrolysis assay (2.012 µg g−1 h−1). Fungal inoculation of VAM in combination with lime + FYM + NPK recorded highest acid and alkaline phosphatase activities (82.20 and 67.02 µg PNP g−1 soil h−1, respectively). Soil biological activities and phosphatase activities had highly significant relationship with tuber yield and biochemical constituents of yam bean. The study emphasized the conjunctive use of soil test–based inorganic fertilizers, lime, and organic manures to enhance the enzymatic activities and to realize higher crop yields of yam bean in acid Alfisols.

Long-Term Effect of Fertilizers and Amendments on Different Fractions of Organic Matter in an Acid Alfisol

ABSTRACTThe effect of fertilizers and amendments on organic matter dynamics in an acid Alfisol was studied in a long-term field experiment initiated during 1972 at experimental farm of Department of Soil Science, CSK HPKV, Palampur (India). Continuous application of chemical fertilizers either alone or in combination with farmyard manure (FYM) or lime for 42 years significantly influenced water-soluble organic carbon (WS-OC), water-soluble carbohydrate (WS-CHO), soil microbial biomass carbon, soil microbial biomass nitrogen, soil microbial biomass phosphorus, soil microbial biomass sulfur, humic acid (HA), and fulvic acid (FA). Continuous cropping without fertilization resulted in depletion to the order of 17, 21, 24, 23, 22, 26, 12, and 18% in WS-OC, WS-CHO, microbial biomass carbon, microbial biomass nitrogen, microbial biomass phosphorus, microbial biomass sulfur, HA, and FA, respectively. Different fractions of soil organic matter were found to be positively and significantly correlated with grain and straw/stover yield of wheat and maize crops.

Fractions of Copper in Soil and Their Contribution to Copper Availability in Rice–Wheat Cropping System under Long-Term Integrated Nutrient Management in an Acid Alfisol

ABSTRACTLong-term effects of integrated application of organics and chemical fertilizers on transformation of copper (Cu) into various chemical pools and their availability under rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system were investigated in the ongoing long-term fertilizer experiment initiated in 1991 kharif season (May–October) at the research farm of Chaudhary Sarwan Kumar Himachal Pradesh Agricultural University on an acidic soil in the Western Himalayas of India. The continuous use of chemical fertilizers alone for 20 years brought about marked depletion in all forms of copper except organically bound Cu (Cu-PYR) compared to buffer plots. Integrated use of organics and chemical fertilizers gave higher content of Cu forms over chemically treated plots except Cu occluded by free oxides (Cu-OX). Residual Cu was the most dominant form of copper contributing about 67% of the total Cu. Soil solution and exchangeable Cu (Cu-CA) was the most important fraction of copper contributing toward DTPA (diethylene triamine pentaacetic acid) extractable Cu. Content of DTPA extractable Cu increased over control when chemical fertilizers were applied in conjunction with different organics, whereas DTPA Cu content declined over control with application of chemical fertilizers alone for the last 20 years.

Influence of Dual Inoculation of AM Fungi and Rhizobium on Growth Indices, Production Economics, and Nutrient Use Efficiencies in Garden Pea (Pisum sativum L.)

ABSTRACTField experimentation was conducted at Palampur, India during 2011–2012 in an acid Alfisol to quantify the influence of integrated use of arbuscular mycorrhizal fungi (AMF), Rhizobium and inorganic nitrogen (N) and phosphorus (P) on growth, productivity, profitability, and nutrient use efficiencies in garden pea (Pisum sativum L.). The experiment was laid out in randomized block design (RBD) replicated thrice comprising 13 treatments involving AMF (Glomus mosseae), Rhizobium (R. leguminosarum), and inorganic N and P fertilizers. The results revealed that dual inoculation of pea seed with AMF and Rhizobium enhanced the plant height, leaf area index, and dry matter accumulation significantly by 19.4 and 13.1, 10.7 and 10.7, and 16.6 and 16.7%, respectively at 60 and 120 days after sowing (DAS). Similarly, dual inoculation exhibited significant respective increases of 9.5 and 14.6% in absolute and crop growth rates over generalized recommended NP potassium (K) dose (GRD) during 60–120 DAS. The dual inoculation led to significant respective increases of 1.0 and 2.2, 1.06 and 1.74, 0.21 and 1.5, and 1.05 and 1.60 folds in partial factor productivity, crop recovery efficiency, physiological efficiency, and % recovery of applied N and P, respectively over GRD. The magnitude of increase in pea productivity, net returns, and boron to carbon (B:C) ratio following dual inoculation was to the tune of 20, 54.4, and 104.1%, respectively over GRD. Dual inoculation also exhibited significant increases of 19.4 and 53.1% in production and monetary efficiencies of pea over GRD. Overall, dual inoculation of AMF and Rhizobium with 75% soil-test-based N and P dose in pea has great potential in enhancing pea productivity, profitability, and nutrient use efficiency besides saving about 25% fertilizer N and P without impairing pea productivity in Himalayan acid Alfisol.