Phosphorus fractions - Keys to soil based P management - TRƯỜNG CÁN BỘ QUẢN LÝ GIÁO DỤC THÀNH PHỐ HỒ CHÍ MINH

Aluminium phosphorus (Al-P) determined by chloro- molybdic-boric acid reagent and chloro- stannous reductant using the soil residue left after saloid-P estimation.. The[r]

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Int.J.Curr.Microbiol.App.Sci (2017) 6(11): 281-294

281

Original Research Article https://doi.org/10.20546/ijcmas.2017.611.033

Phosphorus Fractions- Keys to Soil based P Management M Chandrakala1*, C.A Srinivasamurthy2, V.R.R Parama3,

S Bhaskar4, Sanjeev Kumar5 and D.V Naveen6

1

National Bureau of Soil Survey and Land Use Planning, Regional Centre, Hebbal, Bangalore-560 024, Karnataka, India

2

Director of Research, Central Agricultural University, Imphal, Manipur, India

Department Soil Science and Agricultural Chemistry, UAS, Bangalore-560 065, Karnataka, India

4

Department of Agronomy, UAS, Bangalore-560 065, Karnataka, India

NDRI, Karnal, India

Deptartment of Soil Science and Agricultural Chemistry, Sericulture College, Chintamani, Karnataka, India

*Corresponding author

A B S T R A C T

Introduction

The total phosphorus level of soil is not only low but also P compounds are mostly unavailable for plant uptake The concentrations of phosphorus in the soil solution (intensity) and capacity of the soil to

supply phosphorus to the soil solution are important factors affecting P availability As the basic raw material rock phosphate available in the country is only 10 per cent of the total requirement hence, fertilizer industry

International Journal of Current Microbiology and Applied Sciences

ISSN: 2319-7706 Volume Number 11 (2017) pp 281-294

Journal homepage: http://www.ijcmas.com

Red soils (Alfisols) of Karnataka are low in total and available phosphorus (P) When soluble P sources are added, undergo transformation into unavailable forms with time Native P compounds, some being highly insoluble are unavailable for plant uptake Thus, knowing the changes in P fractions in different soils is much important for P recommendation The objective of the study was to find out the fate of the applied phosphorus in soils of different P fertility in a finger millet-maize cropping system An experiment with creation of five P fertility gradient strips (Very low, Low, Medium, High and Very high) in one and the same field followed by response of finger millet and maize crops to graded levels of P was undertaken at UAS, Bangalore Soil P fractions were determined in a soil after the harvest of maize in a finger millet- maize cropping system There was an increase in total-P, organic-P, reductant soluble-P, occluded-P and calcium-P fractions with the increased gradient strips from very low to very high applied with levels of P Whereas, saloid-P, aluminium-P and iron-P are the slowly and plant available labile-P forms which were decreased as the labile-P fertility gradients and dose of labile-P addition increased There was a direct relationship with addition, fixation and distribution of P fractions Hence, continuous P fertilization can be restricted in soils of high and very high initial P status as the PUE was 20-40 per cent only in general leads to build-up and transformation in to non-labile P forms

K e y w o r d s

Fertility gradients, Finger millet – maize cropping system, Graded levels of P, Soil phosphorus fractions

Accepted: 04 September 2017 Available Online: 10 November 2017

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282 in India is not self sufficient in meeting the requirement of P therefore, depends on imports for the balance of 90 per cent (Chandrakala, 2014)

Phosphorus (P) dynamics in soil and maintenance of its adequate supply are important for sustainability (Song et al.,

2007) The application of P to each crop in a rotation and low recovery of added P has been found to result in its significant build up in soils (Brar et al., 2004) Application of fertilizer phosphorus is essential for raising the available P content in soils in order to meet the crop requirements at different stages of growth The availability of soil P to plants depends on the replenishment of labile P from other P fractions Nwoke et al., (2004) observed that the changes in different inorganic-P fractions in soils under a wide range of management conditions The extent of P depletion ranged from 33 to 129 per cent over a period of 11 years (Nambiar and Ghosh, 1984; Tandon, 1987)

Knowing the initial soil test value and recovery of added phosphates, it will be possible to work out the amount of fertilizer phosphorus needed to build-up the soil phosphate to a given critical limit Soil based P management relies on maintenance of adequate soil P fertility and replenishment of P nutrient removed by harvested grain However, there is a need to know the effect of P addition and distribution in soils of different P status for sustained P management and improved PUE in the region In the light of the above facts, a field experiment was undertaken involving gradient creation followed by response of finger millet (Eleusine coracana L.) - maize (Zea mays L.), are the major crops cultivated in Karnataka among millets and cereals, respectively The objective of the investigation is to assess the availability of phosphorus and their different fractions in soils of different

phosphorus fertility gradients applied with graded levels of P to finger millet- maize cropping system

Materials and Methods

The field experiment comprised of two stages Fertility gradient creation was the preparatory step as per the procedure of Ramamoorthy et al., (1967) followed by finger millet-maize cropping system in the subsequent seasons Experimental site

The experiment was conducted during 2009-2010 at D-16 Block, Zonal Agricultural Research Station (ZARS), GKVK, UAS, Bengaluru which is located in Eastern Dry Zone of Karnataka at latitude of 12058' N and longitude of 75035' E with an altitude of 930 m above mean sea level

Soil characteristics of experiment site Surface soil (0-15 cm) was analyzed for physical and chemical properties and also determined phosphorus fractions by adopting standard procedures Soils are reddish brown laterite derived from gneiss under subtropical semiarid climate The soil of experimental site was red sandy clay loam in texture, acidic in reaction, low in available nitrogen (203.84 kg ha-1) and phosphorus (18.42 kg ha-1) and medium in available potassium (147.12 kg ha-1) content (Table 1)

Experimental details

Creation of fertility gradient strips

Five equal strips (45 × 8.2 m2) were created in one and the same field and named very low (VL), low (L), medium (M), high (H) and very high (VH) gradient strips as P0, P1, P2, P3

and P4, respectively Graded doses of

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283 per cent each so as to achieve Very low (<15 kg P2O5 ha-1), Low (16-30 kg P2O5 ha-1),

Medium (31- 45 kg P2O5 ha-1), High (46 - 60

kg P2O5 ha-1) and Very high (> 60 kg P2O5

ha-1) P levels in the respective strips Exhaustive crop fodder maize (South African tall) was grown provided with recommended doses of nitrogen (100 kg ha-1), phosphorus (50 kg P2O5 ha-1) and potassium (25 kg K2O

ha-1) and green fodder was harvested at 60 days after sowing Soils in each strip analyzed for available nutrients status Available P2O5

content obtained in P0, P1, P2, P3 and P4,was

14.82, 27.37, 38.76, 52.25, 80.72 kg ha-1, respectively

Studies on the changes in soil P and different P fractions

After harvest of exhaustive crop, each strip was divided in to three replications and further each replication was sub divided in to seven treatment plots of equal size Finger millet (GPU-28) was grown (spacing: 20 x 10 cm) during summer followed by maize (Nithyashree Hybrid) was grown (spacing: 60 x 30 cm) during kharif 2011 by imposing treatments in a factorial RCBD design Treatment details as follows; T1: Absolute

control; T2: Package of Practice

(NPK+FYM); T3: 100 % Rec N, P &K only

(no FYM); T4: 75 % Rec P + rec dose of

N&K (no FYM); T5: 75 % Rec P + Rec dose

of N&K only+ Rec FYM; T6: 125 % Rec P

+ Rec dose of N&K (no FYM); T7: 125 %

Rec P + Rec dose of N&K + Rec FYM Recommended dose of fertilizer for finger millet was 50- 40- 25 kg N- P2O5- K2O ha-1

whereas for maize 100-50-25 kg N-P2O5-K2O

ha-1 was given Recommended dose of FYM given was 7.5 t ha-1

Soil sampling and analysis

After the harvest of maize in a finger millet-maize cropping system, The representative

soil samples were collected at 0-15 cm depth from all the plots separately, which were analyzed for available P and their fractions as per the standard procedures as follows Total phosphorus was estimated by vanado-molybdo phosphoric yellow colour method (Hesse, 1971) Organic phosphorus was determined by deducting the sum of total inorganic phosphorus from total phosphorus as suggested by Mehta et al., (1954) The available phosphorus was extracted using Bray’s No.1 extractant for the soils having pH less than 6.5 and Olsen’s extractant for the soils having pH 6.5 and above The extracted phosphorus was estimated by chloro-stannous reduced molybdo-phosphoric blue colour method (Jackson, 1973)

The method outlined by Peterson and Corey (1966) was followed to fractionate soil inorganic phosphorus Saloid-P was estimated by molybdo-sulphuric acid reagent, using stannous chloride as reductant Aluminium phosphorus (Al-P) determined by molybdic-boric acid reagent and chloro-stannous reductant using the soil residue left after saloid-P estimation The soil sediment from Al-P estimation, was then used to determine iron phosphorus (Fe-P) by molybdic-boric acid reagent and chloro-stannous reductant

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284 Data computation

The experimental data were analyzed using ANOVA (One-Way) Critical differences among treatments were estimated at % probability level of significance Correlation studies were made and the values of correlation coefficient (r) were calculated and tested for their significance (Panse and Sukhatme, 1967)

Results and Discussion

Data presented in Table to depicted changes in phosphorus fractions after harvest of maize in a finger millet-maize cropping system which showed significant differences among mean values of P gradients, treatments and their interaction

Fertility gradients effect

There was an increase in, total-P (Table 2), organic-P (Table 3), RS-P (Table 5), occluded-P (Table 6) and Ca-P (Table 6) fractions with the increased fertility gradient strips from very low to very high strip This might be due to application of P in the increasing dose in order to create fertility gradients Enrichment of the total and available P (Fig 1) status as the PUE (Table 8) by the crops was 20-40 per cent only in general There was a positive correlation exists (Table 7a) between T-P and Org-P, RS-P, Occl-P and Ca-P fractions (0.997*, 0.999*, 0.974* and 0.992*, respectively) There were also recorded increased Org-P, RS-P, Occl-P and Ca-P fractions with the increased T-P content of soil

Unlike T-P, org-P, RS-P, occl-P and Ca-P fractions, S-P (Table 3), Al-P (Table 4) and Fe-P (Table 4) fractions were decreased as the P fertility gradients increased This may be due to transformation of these fractions in to non-labile forms of P The Al-P and Fe-P

fractions were higher in very low and low gradient strips, might be due to acidic soil pH resulting in transformation of added P in to Al-P and Fe-P fractions Majumdhar et al.,

(2007) observed that the contribution of Org-P to T-Org-P was 48.90 to 53.70 per cent They also noticed significant increase in S-P, Al-P, Fe-P and Ca-P but decrease in reductant-soluble and occluded-P fractions Setia and Sharma (2007) observed that application of P @ 17.50 or 35 kg P ha-1 increased all the forms of P in 22 years of maize-wheat cycles The relative abundance of P fractions was in the order of saloid-P < Fe-P < Al-P < Ca-P Jakasaniya and Trivedi (2004) also noticed that the increase in S-P, Al-P, Fe-P and Ca-P fractions with increase in rate of P addition in different soils Org-P showed a buildup due to sorghum cropping in all soils

Treatments effect

Application of graded levels of P with gradient strips had direct relationship with quantity and distribution of P fractions The quantity of P fractions was higher as the rate of P application was higher Application of 125 % rec P + rec N&K + rec FYM to very high gradient strip recorded higher T-P and Org-P followed by nutrients application as per package of practice and 125 % rec P + rec N&K Labile-P forms (S-P, Al-P and Fe-P) were higher when P was added along with manure may be due to lesser fixation of P and chelating action of manures which keeps the P in solution there by reducing the transformation of labile P in to non-labile P forms Non labile pool was enriched when P was added at higher rate without manure application Anil kumar (2013) reported that application of manures recorded significantly higher available P over control

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285 comparison to their initial concentration Sukhvir Kaur (2015) reported that the application of integrated fertilizers recorded

significantly higher Sa-P concentration compared to inorganic only

Fig.1 AvP2O5 in soils of different P fertility strips as influenced by graded levels of applied P

Table.1 Initial soil properties of experimental site

Parameters Values

Coarse sand (%) 33.2

Fine sand (%) 36.3

Silt (%) 7.5

Clay (%) 23.0

Textural Class Sandy Clay loam

CEC [c mol (p+) kg-1] 11.10

pH (1:2.5) 5.55

EC (dS m-1) 0.26

Organic Carbon (%) 0.45

Available N (kg ha-1) 203.84

Available P2O5 (kg -1

) 18.4

Available K2O (kg -1

) 147.1

Exchangeable Ca [c mol (p+) kg-1] 6.75 Exchangeable Mg [c mol (p+) kg-1] 3.60

Avail S (mg kg-1) 10.82

DTPA-Fe (mg kg-1) 55.8

DTPA-Mn (mg kg-1) 59.5

DTPA-Cu (mg kg-1) 2.21

DTPA-Zn (mg kg-1) 2.35

B (mg kg-1) 0.54

Phosphorus fractions

Total P (mg kg-1) 1115.0

Saloid–P(mg kg-1) 48.70

Al-P (mg kg-1) 70.52

Fe-P (mg kg-1) 135.66

Reductant soluble-P (mg kg-1) 146.85

Occluded-P (mg kg-1) 11.07

Calcium-P (mg kg-1) 10.53

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286

Table.2 Changes in total soil phosphorus fraction (Total P) after harvest of maize

P levels/Treatments

Total- P(mg kg-1)

P0 P1 P2 P3 P4 Mean

T1 726.33 1086.50 1113.33 1331.67 1517.92 1155.15

T2 1288.67 1543.67 1676.67 1724.67 1810.83 1608.90

T3 1033.33 1220.83 1337.67 1430.42 1563.08 1317.07

T4 959.00 1198.17 1247.75 1436.25 1501.58 1268.55

T5 1121.33 1308.75 1403.75 1538.00 1757.58 1425.88

T6 1075.33 1431.00 1533.67 1694.17 1797.07 1506.25

T7 1381.00 1619.00 1701.33 1890.33 1989.75 1716.28

Mean 1083.57 1343.99 1430.60 1577.93 1705.40 1428.30

F S.Em± CD (p=0.05) CV

P S 37.06 104.58

11.89

T S 43.85 123.74

P x T NS - -

T1: Absolute control P0: Very low Phosphorus fertility strip

T2: Package of Practice (rec NPK+FYM) P1: Low Phosphorus fertility strip

T3: 100 per cent rec N, P & K (no FYM) P2: Medium Phosphorus fertility strip

T4: 75 per cent rec P + rec N&K (no FYM) P3: High Phosphorus fertility strip

T5: 75 per cent rec P + rec N&K+ rec FYM P4: Very high Phosphorus fertility strip

T6: 125 per cent rec P + rec N&K (no FYM)

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287

Table.3 Changes in organic and saloid soil phosphorus fractions (mg kg-1) after harvest of maize

P levels/ Treatments

Org-P S- P

P0 P1 P2 P3 P4 Mean P0 P1 P2 P3 P4 Mean

T1 425.91 646.00 674.71 889.70 1066.52 740.57 47.98 53.81 50.73 39.27 36.07 45.57 T2 691.64 924.07 1105.90 1132.47 1197.97 1010.41 84.07 89.25 54.03 44.60 43.67 63.12 T3 418.03 614.30 758.43 864.18 971.38 725.26 64.82 72.49 49.73 40.23 34.00 52.25 T4 415.16 614.73 725.73 921.25 1065.17 748.41 64.14 77.59 48.43 41.09 36.28 53.51 T5 593.89 722.71 879.12 1020.05 1230.28 889.21 70.73 81.77 55.61 52.89 47.96 61.79 T6 466.37 792.52 933.56 1089.97 1160.29 888.54 50.20 66.47 38.95 39.55 37.93 46.62 T7 706.63 969.11 1141.60 1318.74 1417.07 1110.63 85.84 90.52 45.74 42.21 35.73 60.01 Mean 531.09 754.78 888.43 1033.77 1158.38 873.29 66.83 75.99 49.03 42.83 38.81 54.70

F S.Em± CD (p=0.05) CV F S.Em± CD (p=0.05) CV

P S 12.74 35.96

6.68

S 1.92 5.42

16.11

T S 15.08 42.55 S 2.27 6.42

P x T S 33.72 95.15 S 5.08 14.35