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Prime Journal of Physical Science (PJPS)
Vol. 1(5), pp. 53-57, December 19 th , 2012
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Full Length Research
Effect of humic acid and phosphorus on yield, nutrient
availability in soil and uptake by peas
Sarwar M, Ehsan Akhtar M and Hyder SI
Land Resources Research Institute, National Agricultural research Centre, Islamabad-45500, Pakistan.
Accepted 14 th November, 2012
A field experiment was conducted at experimental area of vegetable programme, NARC, Islamabad, to
investigate the interactive effect of Phosphorus (P) and humic acid (HA) on macro and micro nutrients use
efficiency in soil and their uptake by peas during Rabi 2011. The data translate that soil application of humic
acid at 100 kg ha -1 along with 40 Kg P 2 O 5 ha -1 significantly enhanced green peas’ yield 35% higher than 100%
dose of Phosphorus fertilizer alone. The data revealed that addition of humic acid at 100 kg ha” along with 50%
recommended dose of fertilizer that is, 40 Kg P 2 O 5 ha -1 significantly improved the availability of Phosphorus,
Potassium and micronutrients viz., iron and zinc and enhanced their uptake. Soil application of humic acid at
100 kg ha -1 along with 50% recommended dose of fertilizers improved the availability and uptake of nutrients
than 100% recommended dose of fertilizers alone.
Keywords : humic acid, phosphorus, green peas, iron and zinc.
INTRODUCTION
With the continued and rapid increase in world
population, it has become vital importance to obtain
higher yields per unit area agricultural production. For this
reason the plant’ water and nutrients need must be met.
In our case where soils are predominantly calcareous in
nature, that affect the soil properties related to plant
growth whether they are physical or chemical such as its
fertility. Excess calcium carbonate poses serious
problems to plant nutrition; it raises pH more than 8 of
soil at which plant nutrients are relatively unavailable.
Increased loses of nitrogen ammonia and reduced
solubility of phosphorus (Celik et al., 2008). Since
excessive application of chemical fertilizers may affect
soil health and sustainable productivity. It is imperative to
search for possible alternate organic source that can
sustain soil health and crop production. Humic
substances improve soil fertility by modifying soil physical
and chemical properties (Asik et al., 2009). Humic acid
derived from lignite is the most concentrated form of
organic material and it is a ready source for carbon and
nitrogen.
Humic acid improves the physical, chemical and
biological properties of the soil and influences plant
growth (Chen et al., 2001). Nitrogen and phosphorus are
the most limiting nutrients to vegetative production but
their sufficient use by majority of the smallholder farmers
become limiting due to their high costs.
There are several problems which are impeding the
balance and efficient use of fertilizers. They may be well
addressed by the application of humic acid. It seems that
humic substances may influence both respiration and
photosynthesis (Nardi et al., 2002). Humic substances
have a very profound influence on the growth of plant
roots. When humic acids and fulvic acids are applied to
the soil, enhancement of root initiation and increased root
growth was observed (Pettit, 2004).
The stimulatory effects of humic substances have been
directly correlated with enhanced uptake of
macronutrients, such as nitrogen, phosphorus; sulfur
(Chen et al., 1999), and micronutrients, that is, Fe, Zn,
Cu and Mn (Chen et al., 1999). Humic substances may
possibly enhance the uptake of minerals through the
stimulation of microbiological activity (Mayhew, 2004).
When adequate humic substances are present within the
soil, the requirement for nitrogen, phosphorus and
potassium fertilizer applications may be reduced (Pettit,
2004).
The combined effects of HA and P application was
more effective on growth and growth parameter than
each separate effect. Humic acid application significantly

Sarwar et al., 54
Table-1: Effect of humic acid and phosphorus application on green peas’ yield (t ha -1 )
P Levels
H Levels
1 2 3 4 Means
1 1.75 l 2.30 k 2.66 i 3.04 h 2.44 C
2 2.53 j 3.22 f 4.19 a 4.17 b 3.53 B
3 3.10 g 3.31 e 4.14 c 3.99 d 3.63 A
Means 2.46 D 2.94 C 3.66 B 3.73 A
increased N, P, K, Ca, Mg, S, Mn and Cu contents of
shoot of pepper seedling (K. Mesut 2010). Pea (Pisum
sativum) belongs to family leguminous is a well known
vegetable of the temperate region. This herbaceous plant
is the major food ingredient of vegetarian diet and meets
the dietary requirement of the people throughout the
world. It also contains most of the essential nutrients like
fiber and protein. The pea is a legume with great
nutritional potential because of its high content of protein
(27.8%), complex carbohydrates (42.65%), vitamins,
minerals, dietary fiber and antioxidant compounds
(Urbano et al., 2003). Addition of humic acid with
chemical fertilizer has a long promising effect on crop
production. This research experiment was planned to
access the interactive effect of P and lignite-derived HA
on growth and mineral uptake of peas and soil health.
MATERIALS AND METHODS
A field experiment was conducted in the farm area of the
Vegetable Programme (LRRI), National Agricultural
Research Centre (NARC), Islamabad, Pakistan, in soil
representing ( clay loam in texture, pH 8.4, ECe 0.29
dSm -1 , low in available NO 3 nitrogen (0.64 mg kg -1 ), low in
available phosphorus (3 mg kg -1 ) and adequate in
available potassium (50 mg kg -1 ). The plots were
assigned according to their respective treatments and
arranged in randomized complete block design (RCBD)
under two factors (HA and P levels). Humic substances
have characteristics of pH 7.83, EC 0.94 and OM 68% N,
P and K were 3.40, 0.15 and 3.42% respectively. Basal
dose of N and K was uniformly applied to all plots. The
treatments were:
Factor 1: Fertilizer levels
P1: Control
P2: 50% Recommended Dose of P (40 Kg P 2 O 5 ha -1 )
P3: 100% Recommended Dose of P (80 Kg P 2 O 5 ha -1 )
Factor 2: Humic acid levels
HA1: Control (No humic acid)
HA2: Soil application of HA at 50 kg ha -1
HA3: Soil application of HA at 100 kg ha -1
HA4: Soil application of HA at 150 kg ha -1
Soil samples were collected before sowing and at harvest
stage and analysed for available P, K, Zn, Mn and Fe
following standard procedures (ABDTPA). Data on yield
parameters like green peas’ yield (table-1) were also
recorded. Plant samples were analysed for the content of
P, K, Mn and Zn adopting standard analytical methods.
The data thus obtained were subjected for statistical
analysis using MSTATC package.
RESULTS, DISCUSSION AND CONCLUSION
Green Peas’ Yield (t ha -1 )
The data pertaining to green pea’s yield of the
experiment is mentioned in table 1. It reveals that there
was significant effect of humic acid and P on green peas
yield .The highest peas yield (4.19 t ha -1 ) was attained in
treatment where humic acid was applied at 100 kg ha -1
along with 50% dose of Phosphorus (40 Kg P 2 O 5 ha -1 ) . It
was 35% more than the treatment receiving 100% dose
of Phosphorus fertilizer application alone (80 Kg P 2 O 5 ha -
1 ). Significant effect of humic acid on pea’s yield is the
result of sustained macro and micro nutrients availability
to plants through out growing season as humic acid
reduces P, K and Zn fixation through chelation by David
et al., (1994). Secondly HA Inhibit of urease activity by
HA (Vaughan and Ord, 1991), led to reduced losses of N
by volatilization, as described by Flaig (1984) could have
also contributed to increased availability of nitrogen. In
the light of available nutrients, soil application of humic
acid at 100 kg ha -1 significantly favoured the uptake of P,
K, Fe and Zn which ultimately increased the yield.
Available Phosphorus (mg kg -1 )
Phosphorus content in the soil was positively affected with
applied HA levels. Results indicated in table 2 confirm soil P
content was increased by increasing HA levels. The highest
concentration of soil P (5.1 mg kg -1 ) was observed with the
application of (HA) 150kgha -1 along with P 80kgha -1 which
was 70% higher than control .It shows that humic acid
application significantly reduce the phosphorus fixation
and increase its availability through chelation effect This is
in consonance with the findings of David et al., (1994).
Who reported due to that slow and continuous dissolution
of phosphate minerals in soil by humic acid increased P
availability (Pal and Sengupta, 1985). The soil
phosphatase activity improved by humic acid might have
resulted in increased P availability as phosphatase
hydrolyses the phosphate esters into inorganic
phosphorus Malcolm and Vaughan (1979). Heng (1989)
reported that HA reduces P fixing capacity of the soil,
which closely corroborate with the present study where
HA enhanced the P availability.

55 Prim. J. Phys. Sci.
Table-2: Effect of Humic Acid and Phosphorus Application on P (mg kg -1 ) in Soil
P Levels
H Levels
1 2 3 4 Means
1 3 g 3.93 e 4.43 d 4.66 c 4 B
2 3.16 fg 4.3 d 4.44 d 4.9 b 4.2 AB
3 3.23 f 4.3 d 4.93 b 5.1 a 4.39 A
Means 3.13 D 4.17 C 4.6 B 4.88 A
Table-3: Effect of Humic Acid and Phosphorus Application on K (mg kg -1 ) in Soil
P Levels
H Levels
1 2 3 4 Means
1 50 j 55 h 64 f 77 d 61 C
2 51 i 64 f 77 d 94 b 71 B
3 59 g 66 e 78 c 111 a 78 A
Means 53 D 61 C 73 B 94 A
Table-4: Effect of Humic Acid and Phosphorus Application on Zn (mg kg -1 ) in Soil
P Levels
H Levels
1 2 3 4 Means
1 0.44 e 0.53 d 0.72 ab 0.77 ab 0.61 C
2 0.61 c 0.74 ab 0.77 ab 0.78 ab 0.72 B
3 0.65 c 0.74 ab 0.78 ab 0.79 a 0.74 A
Means 0.56 D 0.67 C 0.75 B 0.78 A
Table-5: Effect of Humic Acid and Phosphorus Application on Mn (mg kg -1 ) in Soil
P Levels
H Levels
1 2 3 4 Means
1 4.92 j 6.36 g 7.16 e 7.27 d 6.42 C
2 5.79 i 6.70 f 7.28 d 7.36 c 6.78 B
3 5.95 h 6.74 f 7.76 b 8.16 a 7.15 A
Means 5.55 D 6.60 C 7.40 B 7.59 A
Table-6: Effect of Humic Acid and Phosphorus Application on Fe (mg kg -1 ) in Soil
P Levels
H Levels
1 2 3 4 Means
1 18.96 j 21.15 i 24.04 f 26.12 c 22.56 C
2 21.44 h 21.58 h 24.59 e 26.45 b 23.94 B
3 21.97 g 22.18 g 25.18 d 26.99 a 24.08 A
Means 20.79 D 21.63 C 24.60 B 26.52 A
Available Potassium (mg kg -1 )
Potassium content in the soil were also positively affected
with HA application. Results indicated in table 3 show soil K
content increased by increasing HA. The highest
concentration of soil K (111 mg kg -1 ) was observed with the
application of (HA) at 150kgha -1 along with P at 80kgha - 1
which was 122% more than control. The results are in
agreement with this finding of Tan (1978) and K. Mesut
(2010) who reported that humic acid released the fix K.
Available Zinc, Manganese and Iron (mg kg -1 )
The data pertaining to micronutrients (Zn, Mn, Fe) is
presented in tables (4, 5, 6), the data showed that HA and P
application increased Zn, Mn and Fe contents in soil.
Maximum Zn, Mn and Fe contents in soil were observed in
the treatment where HA was applied at, 150kg ha -1 with 80kg
ha -1 P. The humic acid application increased Zn 79%, Mn
66% and Fe 42% over control respectively. The possible
reasons for increased availability of zinc by humic acid

Sarwar et al., 56
Table-7: Effect of Humic Acid and Phosphorus Application on P (%) Uptake
P levels
Humic acid levels
H1 H2 H3 H4 Mean
P1 .15 e .16 de .17 cde .17 cde .15 B
P2 .18 bcd .19 abc .21 a .20 ab .17 B
P3 .19 abc .20 ab .21 a .21 a .20 A
Mean .16 B .17 AB .17 AB .18 A
Table-8: Effect of Humic Acid and Phosphorus Application on K (%) Uptake
P levels
Humic acid levels
H1 H2 H3 H4 Mean
P1 1 h 1.3 g 1.4 f 1.4 f 1.27 C
P2 1.4 f 1.6 e 1.7 d 1.9 c 1.65 B
P3 1.6 e 1.9 c 2.0 b 2.2 a 1.93 A
Mean 1.33 D 1.60 C 1.70 B 1.83 A
Table-9: Effect of Humic Acid and Phosphorus Application on Zn (mg Kg -1 ) uptake
P levels
Humic acid levels
H1 H2 H3 H4 Mean
P1 30 j 36 h 37 g 40 f 36 C
P2 31 i 42 e 42 e 48 c 41 B
P3 40 f 45 d 51 b 55 a 47 A
Mean 34 D 41 C 43 B 47 A
Milap Chand et al. (1980) is increased solubility of zinc
and ability of humic acid to form stable complexes with
zinc. Enhanced solubilisation and increased extractability
of iron and reduction of non-available iron oxide forms to
available forms by humic acid may account for its
increased availability as reported by Varadachari et al.
(1997).
Phosphorus Content in Peas (%)
Phosphorus content in peas plant significantly increased with
combined application of HA and P levels. Results indicated in
table 7 confirm peas plant P content was increased by
increasing HA. The highest concentration of peas plant P
(.21%) was observed with the application of (HA) at 150kgha -
1 along with P at 80kgha -1 which was 28% more than control.
The increase in P uptake may be due to the prevention of
P fixation in the soil and the formation of humophospho
complexes, which are easily assimilable by the plants
(Raina and Goswami, 1988). Addition of humic acids to
soil with P fertilizer significantly increases the amount of
water-soluble phosphate, strongly retarded the formation
of occluded phosphate, and increased P uptake by plants
Wang et al. (1995).
Potassium Content in Peas (mg kg -1 )
Potassium content in pea’s plant was positively affected by
application of HA along with P levels. Results indicated in
table 8 reveal peas plant K content was increased by
increasing HA. The highest concentration of peas plant P
(2.2%) was observed with the application of (HA) at 150kgha -
1 along with P at 80kgha -1 which was 35% more than the
treatment receiving 100% dose of Phosphorus fertilizer
application alone. According to Samson and Visser
(1989), humic acid induced increase in permeability of
biomembranes for electrolytes accounted for increased
uptake of K.
Zinc Content in Peas (mg kg -1 )
The data pertaining to micronutrient (Zn,) is presented in table
9, the data showed that HA and P application increased Zn,
content in peas plant. Results indicated that max Zn, content
in peas plant was observed in the treatment where HA was
applied at, 150kg ha -1 and 80kg ha -1 P. The humic acid
application increased Zn 83% over control. Similar findings

57 Prim. J. Phys. Sci.
Table- 10: Effect of Humic Acid and Phosphorus Application on Mn (mg Kg -1 ) Uptake
P levels
Humic acid levels
H1 H2 H3 H4 Mean
P1 9 h 10 g 10 g 12 f 10 C
P2 15 e 18 c 18 c 19 b 18 B
P3 17 d 18 c 19 b 21 a 19 A
Mean 13 D 15 C 16 B 17 A
were reported by Demir et al, (1999) and Chen et al,
(2001) in cucumber. The beneficial effect of humic acid in
soil might have prevented the formation of insoluble
complexes of zinc and facilitated their uptake by plants
Manganese Content in Peas (mg kg -1 )
The data pertaining to micronutrient (Mn,) is presented in
table 10, the data showed that HA and P application
increased Mn, content in peas plant. Results indicated that
max Mn, content in peas plant was observed in the treatment
where HA was applied at, 150kg ha -1 and 80kg ha -1 P. The
humic acid application increased Mn 133% over control. It
might be due to the increased solubilization (Varadachari
et al., 1997).
REFERENCES
Asik BB Turan MA Celik H Katkat AV Effect of humic
substances to dry weight and mineral nutrients uptake
of wheat on saline soil conditions // Asian Journal of
Crop Science.- 2009, vol. 1, iss. 2, p. 87-95
Celik H Katkat AV Asik BB Turan MA Effect of soil
application of humus on dry weight and mineral
nutrients uptake of maize under calcareous soil
conditions // Archives of Agronomy and Soil Science.-
2008., Vol. 54, iss. 6, p. 605-614
Chen Y Magen H and Clapp CE (2001). Plant growth
stimulation by humic substances and their complexes
with iron. Proceedings of International Fertiliser
Society. Israel. Pp.14,
Chen Y Clapp CE Magen H Cline VW (1999). Stimulation
of plant growth by humic substances: Effects on iron
availability. In: Ghabbour, EA, Davies G. (eds.),
Understanding humic substances: Advanced methods,
properties and applications. Royal Society of
Chemistry, Cambridge, UK. pp. 255-263
David PP Nelson Pv and Sanders DC (1994). A humic
acid improves growth of tomato seedling in solution
culture. J. Pl. Nutr., l7(l): 173-184.
Flaig W (1984). Soil organic matter as a source of
nutrients. In: Organic matter and rice, Internat ional
Rice Research Institute,Manila, Philippines, pp. 73-92.
Heng LC (1989). Influence of humic substances on P-
sorption in Malaysian soils under rubber. J. Natural
Rubber Res., 4(3): 186-194.
Mayhew L (2004). Humic substances in biological
agriculture [Online]. Available at
ww.acresusa.com/toolbox/reprints/Jan04_Humic%20S
ubstances.pdf(2004)
Malcolm R.E. and Vaughan, D. (1979). Humic
substances and phosphatase activities inplant tissues.
Soil Biol. Biochem., 11: 253- 259. 673
Mesut K Cimrin Önder Türkmen Metin Turan and Burcu
Tuncer (2010) Phosphorus and humic acid application
alleviate salinity stress of pepper seedling. African
Journal of Biotechnology Vol. 9(36), pp. 5845-5851.
Milap Chand NS Randhawa and Sinha MK (1980). Effect
of gypsum, pressmud, fulvic acid and zinc sources on
yield and zinc uptake by rice crop in a saline-sodic soil.
Pl. Soil,55: 17-24.
Nardi S Pizzeghello D Muscolo A Vianello A (2002).
Physiological Effects of humic ubstances in plant
growth. Soil Biol. Biochem., 34(11): 1527-1536
Pal S and Sengupta MB (1985). Nature and properties of
humic acid prepared from different sources and its
effect on nutrient availability. Pl. Soil. 88(1): 71-79.
Pettit RE (2004). Organic matter, humus, humate, humic
acid, fulvic acid and humin: their importance in soil
fertility and plant health [Online]. Available at
www.humate.info/mainpage.htm.
Tan KH (1978). Effects of humic acid and fulvic acids on
release of fixed potassium. Geoderma, 21: 67-74.
Varadachari C Chattopadhyay T and K Ghosh. 1997
Complexation of humic substances
with oxides of iron and aluminum. Soil science. v. 162 (1)
Pages: p. 28-34.
Vaughan D and Ord BG (1991). Influence of natural and
synthetic humic substances on the activity of urease. J.
Soil Sci., 42: 17-23.
Wang XJ Wang ZQ and SGLi 1995 The effect of humic
acids on the availability of phosphorus fertilizers in
alkaline soils. Soil Use Manage. v. 11 (2) p. 99-102.