Influence of humic acid and poultry manure on nutrient content and their uptake by T. aman rice

A study was conducted to examine the nutrient content and their uptake of rice as influenced by the application of humic acid (HA) and poultry manure (PM). This experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. Three levels each of humic acid (0, 3 and 6 L ha -1 ) and poultry manure (0, 3 and 6 t ha -1 ) were applied. BRRI dhan39 was used as test crop. Basal doses of N, P, K and S fertilizers were applied. Both humic acid and poultry manure either singly or in combination significantly affected the contents and uptake of N, P, K, S, Ca and Mg of BRRI dhan39. The maximum content of N, P, K, S and Ca except Mg and their uptake were recorded from the treatment combination of 6 L ha -1 humic acid along with 3 t ha -1 poultry manure.


Introduction
Rice is the main staple food of Bangladesh.The annual rice production in Bangladesh is about 4,37,29,000 metric tons (IRRI, 2006).The average yield of rice is 3.90 t ha -1 (BRRI, 2007).In Bangladesh, most of the cultivated soils have less than 1.5% organic matter.Continuous use of chemical fertilizers accelerated the depletion of soil organic matter and impairs physical and chemical properties of soil in addition to causing micronutrient deficiencies.This important component of soil is declining with time.Humic acid is one of the major components of humic substances.Humic matter is formed through the chemical and biological humification of plant and animal matter and through the biological activities of microorganisms (Anonymous, 2010).Humic acid improves the physical, chemical and biological properties of the soil and influences plant growth.Humic substances are recognised as a key component of soil fertility properties, since they control chemical and biological properties of the rhizosphere (Rengrudkij and Partida, 2003, Nardi et al., 2005, Trevisan et al., 2009).The effects of humic substances have been directly correlated with enhanced uptake of macronutrients, such as N, P and S, and micronutrients like Fe, Zn, Cu and Mn (Pettit, 2004, Chen et al., 2001).The mechanism of humic acid activity in promoting plant growth is not completely known, but several explanations have been proposed by some researchers such as increasing cell membrane permeability, oxygen uptake, respiration and photosynthesis, phosphate uptake, and root cell elongation (Cacco and Dell'Agnolla, 1984;Türkmen et al., 2004;Petronio et al., 1982).Poultry manure is an excellent source of nutrients and can be incorporated into most of the fertilizer programs.Those using manures must practice sound soil fertility management to prevent nutrient imbalances and associated animal health risks as well as surface-water and groundwater contamination.Global environment pollution can also be reduced considerably by reducing the use of chemical fertilizers and increasing the use of cowdung, poultry manure, rice straw and others.Hence a study aiming at the effect of humic acid and poultry manure on nutrient content and their uptake by rice was undertaken.

Materials and Methods
The experiment was conducted at central farm of Bangladesh Agricultural University, Mymensingh from August to November, 2010.Rice cultivar BRRI dhan39 was used as test crop.There were 9 treatments consisting of three rates of humic acid (0, 3 and 6 L ha -1 ) and three rates of poultry manure (0, 3 and 6 t ha -1 ). Humic acid was collected from Global Agrovat Company Limited and poultry manure was collected from the Poultry Farm of Bangladesh Agricultural University, Mymensingh.Humic acid was used in liquid form.The experimental treatments were T 0 = HA 0 +PM 0 (control), T 1 = HA 0 +PM 3 , T 2 = HA 0 +PM 6 , T 3 = HA 3 +PM 0 , T 4 = HA 3 +PM 3 , T 5 = HA 3 +PM 6 , T 6 = HA 6 +PM 0 , T 7 = HA 6 +PM 3 and T 8 = HA 6 +PM 6 .The doses of N, P, K and S fertilizers were as per the recommendations made by Bangladesh Rice Research Institute (BRRI) and that was 150 kg ha gypsum.Land was prepared by ploughing and cross-ploughing with the help of power tiller and leveled with ladder.The experiment was laid out in a randomized complete block design with three replications.The unit plot size was 10 m 2 (4.0 m x 2.5m).25 day old seedlings were transplanted with the spacing of 15 cm x 20 cm.Intercultural operations were practiced as and when necessary.The crop was harvested on 17th November, 2010.The plant was threshed and grain and straw was collected plot-wise.The soil sample was analyzed for particle size, pH and determination of organic matter, total N, available P, exchangeable K, cation exchange capacity and plant sample was analyzed for determination of N, P, K, S, Ca and Mg dontents.Grain and straw samples were dried in an oven at 65 0 C for 48 hours and then ground after cooling.Grain and straw samples were digested by wet oxidation method using diacid mixture (HNO 3 :HClO 4 = 2:1) for the analysis of nutrients under consideration as described by Jackson (1962).The content of N was determined by semi-micro kjeldahl method followed by Jackson (1962).The concentrations of P and S were analysed with the help of a spectrophotometer at 660 and 420 nm wavelength, respectively (Jackson, 1962;Tandon, 1995).Potassium concentration was determined directly with the help of a flame photometer (Jackson, 1962).The contents of Ca and Mg were determined by EDTA titrimetric method (Page et al., 1982).Nutrient uptake was calculated by the following formula: Nutrient uptake (kg ha ) 100 Data were statistically analyzed using the MSTAT statistical Computer Package Programme (Gomez & Gomez, 1984).

Results and Discussion
Nutrient contents of rice grain and straw Nitrogen: Nitrogen content was significantly influenced by the application of humic acid and poultry manure in grain and straw.The highest N content was obtained in both grain (1.38%) and straw (0.89%) by the application of 6 L ha -1 humic acid and the lowest (1.29% and 0.44%, respectively) was recorded in control (Table 1).These findings were partially supported by Govindasamy and Chandrasekaran (2002) who stated that the addition of humic acid was found to increase the content and enhance the uptake of N, P, K, Ca, Mg, Fe, Mn and Zn by rice.The highest N content (1.37 %) in grain was obtained by the application of 6 t ha -1 poultry manure which was similar to 3 t ha -1 and the lowest N content (1.28 %) was recorded at control (Table 2).The highest N content (0.74 %) in straw was recorded by the application of 6 t ha -1 poultry manure and the lowest (0.59 %) was at PM 0 .The interaction effect of humic acid and poultry manure was statistically significant in grain (Table 3).The highest N content (1.43%) was obtained in grain by the combined application of 6 L ha -1 humic acid and 3 t ha -1 poultry manure while the lowest N content (1.21%) was found in T 0 (control) treatment.Interaction effect of humic acid and poultry manure was insignificant in straw for N content.
Phosphorus: Phosphorus content in grain and straw was significantly influenced by the application of humic acid and poultry manure.The highest phosphorus content in grain (0.26%) and straw (0.19%) was recorded by the application of 6 L ha -1 humic acid and the lowest (0.23% and 0.12%, respectively) was found in HA 0 (Table 1).At optimum level of HA, the roots were highly branched and this might have resulted an increase in surface area, which would have facilitated more efficient nutrient absorption (Mallikarjunarao et al., 1987).The highest P content (0.25%) in grain was observed by the application of 6 t ha -1 poultry manure which was similar to 3 t ha -1 and the lowest content (0.23%) was recorded in PM 0 (Table 2).The highest P content (0.18%) in straw was obtained by the application of 6 t ha -1 poultry manure and the lowest (0.15%) was found in PM 0 .This might be due to the application of poultry manure, which decreased the adsorption capacity and increased soluble P and phosphorus desorption (Amanullah et al., 2007).The P content in grain and straw was significantly influenced by the interaction effect of humic acid and poultry manure (Table 3).The highest P content (0.27%) was obtained in grain at T 7 treatment by the combined application of 6 L ha -1 humic acid and 3 t ha -1 poultry manure followed by T 5 , T 6 and T 8 treatments.The lowest content (0.21%) was found in T 0 .The highest P content (0.21%) was obtained in straw at T 7 treatment by the combined application of 6 L ha -1 humic acid and 3 t ha -1 poultry manure and the lowest content (0.09%) was found in T 0 (control) treatment.Potassium: The content of K in grain and straw was significantly influenced by the application of humic acid and poultry manure.The highest K content in grain (0.81%) and straw (1.37%) was obtained by the application of 6 L ha -1 humic acid and the lowest content (0.63 and 1.00%, respectively) was obtained in HA 0 (Table 1).The highest K content in grain (0.85%) and straw (1.28%) was obtained by the application of 3 t ha -1 poultry manure and the lowest content (0.54% and 1.11%, respectively) was found in PM 0 (Table 2).The interaction effects of humic acid and poultry manure on K content in grain was significant though it was not significant in straw (Table 3).The highest K content (0.97%) in grain was observed by the combined application of 6 L ha -1 humic acid and 3 t ha -1 poultry manure and the lowest content (0.06%) was found in T 0 (control) treatment.
Sulphur: The content of S in grain and straw was significantly influenced by the incorporation of humic acid and poultry manure.The highest S content in grain (0.162%) and straw (0.091%) was obtained by the application of 6 L ha -1 humic acid and the lowest content (0.146 and 0.047%, respectively) was obtained in HA 0 (Table 1).The highest S content in grain (0.16%) and straw (0.080%) was recorded by the application of 6 t ha -1 poultry manure and the lowest (0.15% and 0.064%, respectively) was obtained in PM 0 (Table 2).The interaction effects of humic acid and poultry manure increased S content significantly in grain (Table 3).The highest S content (0.19%) in grain was observed by the combined application of 6 L ha -1 humic acid and 3 t ha -1 poultry manure and the lowest (0.13%) was found in T 0 (control) treatment.There was no significant interaction effect of humic acid and poultry manure on S content in straw.
Calcium: Calciam content in grain and straw was significantly influenced by the application of humic acid and poultry manure.The highest Ca content (0.27%) in grain was obtained by the application of 3 L ha -1 humic acid followed by 6 L ha -1 and the lowest concentration (0.15%) was in control.In straw, the highest Ca content (0.69%) was recorded by the application of 6 L ha -1 humic acid and the lowest (0.43%) was in HA 0 (Table 1).The highest Ca content was obtained in grain (0.27%) and straw (0.65%) by the application of 6 t ha -1 poultry manure and the lowest content (0.18% and 0.50%, respectively) was found in PM 0 (Table 2).The interaction effect of humic acid and poultry manure significantly increased the Ca content Influence of humic acid and poultry manure on T. aman rice in grain (Table 3).The highest Ca content (0.29%) was obtained in grain by the combined application of 6 L ha -1 humic acid and 3 t ha -1 poultry manure and the lowest value (0.02%) was found in control (T 0 ) treatment.There was no significant interaction effect of humic acid and poultry manure on Ca content in straw.
Magnesium: The content of Mg in grain and straw was significantly influenced by the application of humic acid and poultry manure.The highest Mg content (0.23%) in grain was obtained by the application of 3 L ha -1 humic acid and the lowest value (0.16%) was obtained in HA 0 (Table 1).The highest Mg content (0.82%) in straw was found by the application of 6 L ha -1 humic acid and the lowest (0.59%) was recorded in HA 0 .The highest Mg content (0.23%) was recorded in grain by the application of 3 t ha -1 poultry manure and the lowest value (0.19%) was observed in PM 0 (Table 2).The highest Mg content (0.77%) was obtained in straw by the application of 6 t ha -1 poultry manure and the lowest value (0.67%) was found in PM 0 .Magnesium content was significantly influenced due to the combined application of humic acid and poultry manure in the grain and straw of rice (Table 3).The highest Mg content in grain (0.24%) and straw (0.84%) was obtained by the combined application of 6 L ha -1 humic acid and 6 t ha -1 poultry manure and the lowest content(0.13and 0.53%, respectively) was found in control (T 0 ) treatment.

Nutrient uptake by rice grain and straw
Nitrogen: Nitrogen uptake by grain and straw of BRRI dhan39 was significantly influenced by the application of humic acid and poultry manure.The highest N uptake in grain (44.16 kg ha -1 ) and straw (75.21 kg ha -1 ) was obtained by the application of 6 L ha -1 humic acid and the lowest uptake (39.86 and 36.17kg ha -1 , respectively) was found in HA 0 (Table 4).Saalbach (1956) stated that humic acid enhanced the uptake and content of nitrogen in rye.The highest N uptake was obtained in grain (46.88 kg ha -1 ) and straw (69.09 kg ha -1 ) by the use of 6 t ha -1 poultry manure and the lowest uptake (37.26 and 50.19 kg ha -1 , respectively) was recorded in PM 0 (Table 5).The uptake of N by grain and straw of BRRI dhan39 was significantly increased due to the interaction effects of humic acid and poultry manure (Table 6).The highest N uptake in grain (58.20 kg ha -1 ) and straw (97.66 kg ha -1 ) was obtained by the combined application of 6 L ha -1 humic acid and 3 t ha -1 poultry manure and the lowest uptake (28.68 and 28.73 kg ha -1 , respectively) was found in control (T 0 ) treatment.Table 4. Effect of humic acid on the N, P, K, S, Ca and Mg uptake by T. aman rice Treatments N (kg ha -1 ) P (kg ha -1 ) K (kg ha -1 ) S (kg ha -1 ) Ca (kg ha -1 ) Mg (kg ha Phosphorus: The uptake of P by both grain and straw of BRRI dhan39 was significantly influenced by the application of humic acid and poultry manure.The highest P uptake in grain (8.32 kg ha -1 ) and straw (16.06 kg ha -1 ) was recorded at HA 3 .The lowest uptake (7.11 and 9.86 kg ha -1 , respectively) was found at HA 0 (Table 4).Different levels of humic acid had significant effect on nitrogen and phosphorus uptake by oats.The efficiency indices of various humic acids ranged between 25 and 65 per cent (Mishra and Srivastava, 1988).The highest P uptake in grain (8.48 kg ha -1 ) and straw (16.35 kg ha -1 ) was obtained in PM 6 i.e. the application of 6 t ha -1 poultry manure and the lowest uptake (6.84 and 12.59 kg ha -1 , respectively) was found in PM 0 (Table 5).Anion exchange phenomenon could be another reason for increasing P availability and higher P uptake by rice (Deb and Datta, 1967).The difference in P uptake by grain and straw due to interaction effects of humic acid and poultry manure was also significant (Table 6).The highest P uptake in grain (10.99 kg ha -1 ) and straw (21.29 kg ha -1 ) was obtained by the combined application of 6 L ha -1 humic acid and 3 t ha -1 poultry manure and the lowest uptake (4.98 and 7.18 kg ha -1 , respectively) was found in control (T 0 ) treatment.Jelanic et al. (1966) reported that HA from lignite increased P content and uptake in maize plants.
Potassium: Potassium uptake by both grain and straw of BRRI dhan39 was significantly influenced by the application of humic acid and poultry manure.The highest K uptake in grain (25.92 kg ha -1 ) and straw (115.77kg ha -1 ) was obtained by the application of 6 L ha -1 humic acid and the lowest uptake (19.47 and 82.20 kg ha -1 , respectively) was found in HA 0 (Table 4).The highest K uptake in grain (28.12 kg ha -1 ) and straw (117.55 kg ha -1 ) was obtained by the application of 6 t ha -1 poultry manure and the lowest value (17.04 and 93.10 kg ha -1 , respectively) was found in PM 0 (Table 5).The uptake of K was significantly influenced in grain due to the interaction effect of humic acid and poultry manure (Table 6).The highest K uptake in grain (39.48 kg ha -1 ) was obtained by the combined use of 6 L ha -1 humic acid and 3 t ha -1 poultry manure and the lowest uptake (1.42 kg ha -1 ) was found in T 0 .The uptake of K was not significantly influenced in straw due to the interaction effect of humic acid and poultry manure.Sulphur: The uptake of S by both grain and straw was significantly influenced due to the application of humic acid and poultry manure.The highest S uptake in grain (5.18 kg ha -1 ) and straw (7.69 kg ha -1 ) was obtained by the application of 6 L ha -1 humic acid and the lowest uptake (4.51 and 3.86 kg ha -1 , respectively) was found in HA 0 (Table 4).Raina and Goswami (1988) reported a significant increase in the uptake of N, P, Cu, S and Fe upto 20 ppm carbon as humic acid over control.The highest S uptake in grain (5.38 kg ha -1 ) and straw (7.46 kg ha -1 ) was obtained by the use of 6 t ha -1 poultry manure and the lowest value (4.40 and 5.48 kg ha -1 , respectively) was found in PM 0 (Table 5).Sulphur uptake was significantly influenced in grain due to the interaction effects of humic acid and poultry manure (Table 6).The highest S uptake in grain (7.73 kg ha -1 ) was obtained by the combined use of 6 L ha -1 humic acid and 3 t ha -1 poultry manure and the lowest uptake (3.08 kg ha -1 ) was found in T 0 treatment.The uptake of S was not significantly influenced in straw due to the interaction effects of humic acid and poultry manure.
Calcium: Calcium uptake by both grain and straw of BRRI dhan39 was significantly influenced by the application of humic acid and poultry manure The highest Ca uptake in grain (8.37 kg ha -1 ) and straw (58.31 kg ha -1 ) was obtained by the application of 3 and @ 6 L ha -1 humic acid, respectively and the lowest uptake (4.64 and 35.35 kg ha -1 , respectively) was found in HA 0 (Table 4).The highest Ca uptake in grain (9.07 kg ha -1 ) and straw (60.32 kg ha -1 ) was obtained by the application of 6 t ha -1 poultry manure and the lowest value in grain (5.54 and 42.09 kg ha -1 , respectively) was found in PM 0 (Table 5).The uptake of Ca was significantly influenced in grain due to the interaction effect of humic acid and poultry manure (Table 6).The highest Ca uptake in grain (11.80 kg ha -1 ) was obtained by the combined use of 6 L ha -1 humic acid and 3 t ha -1 poultry manure and the lowest uptake (0.47 kg ha -1 ) was found in T 0 .The uptake of Ca was not significantly influenced in straw due to the interaction effect of humic acid and poultry manure.
Magnesium: Magnesium uptake by both grain and straw of BRRI dhan39 was significantly influenced due to the application of humic acid and poultry manure.The highest Mg uptake in grain (7.13 kg ha -1 ) and straw (69.29 kg ha -1 ) was obtained by the application of 3 and @ 6 L ha -1 humic acid, respectively and the lowest uptake (4.94 and 48.50 kg ha -1 , respectively) was found when 0 L ha -1 humic acid was applied (Table 4).Application of 10 kg HA ha -1 as potassium humate along with 75% recommended doses of fertilizers found to increase the crude protein content and mineral nutrition (P, K, Ca, Mg, Zn, Cu, Fe and Mn) of Amaranthus (Bama and Selvakumari, 2001).The highest Mg uptake in grain (6.99 kg ha -1 ) and straw (71.44 kg ha -1 ) was obtained by the application of 3 and 6 t ha -1 poultry manure, respectively and the lowest uptake (5.69 and 56.29 kg ha -1 , respectively) was found in PM 0 (Table 5).The uptake of Mg by both grain and straw was significantly influenced due to the interaction effects of humic acid and poultry manure (Table 6).The highest Mg uptake in grain (9.77 kg ha -1 ) and straw (86.35 kg ha -1 ) was recorded at T 8 treatment by the combined use of 6 L ha -1 humic acid and 6 t ha -1 poultry manure.The lowest uptake in grain and straw (3.08 and 42.29 kg ha -1 , respectively) were found in treatment T 0 (control) treatment.

Conclusion
Nutrient content in both grain and straw were significantly influenced by the application of HA and PM along with recommended doses of chemical fertilizers.The highest N, P, K, S, and Ca contents in grain and straw were obtained from T 7 treatment.Only the highest content of Mg in grain and straw was found in T 8 treatment.Control treatment gave the lowest content in all the parameters studied.However, the application of 3 t ha -1 PM along with 6 L ha -1 HA showed the better performance than PM or HA alone.It is, therefore, concluded that the incorporation of 6 L ha -1 HA plus 3 t ha -1 PM with recommended doses of N, P, K,S, Ca and Mg fertilizers should be used for T. aman rice particularly BRRI dhan39.

Table 1 .
Effect of humic acid on nutrient contents of T. aman rice

Table 3 .
Interaction effects of humic acid and poultry manure on nutrient contents of T. aman rice

Table 5 .
Effect of poultry manure on the N, P, K, S, Ca and Mg uptake by T. aman rice

Table 6 .
Interaction effect of different doses of humic acid and poultry manure on N, P, K, S, Ca and Mg uptake by T. aman rice