Legume Research

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Legume Research, volume 44 issue 9 (september 2021) : 1046-1052

Effect of Organic and Inorganic Nutrient Sources on Growth, Yield, Nutrient Uptake and Economics of Fodder Cowpea [Vigna unguiculata (L.) Walp.]

Susanta Dutta1, Magan Singh1,*, Rajesh Kumar Meena1, Santosh Onte1, Nirmalendu Basak2, Sanjeev Kumar1, V.K. Meena1
1ICAR- National Dairy Research Institute, Karnal-132 001, Haryana, India.
2Division of Soil Science, ICAR-Central Soil Science Research Institute, Karnal-132 001, Haryana, India.
  • Submitted21-06-2019|

  • Accepted28-12-2019|

  • First Online 17-02-2020|

  • doi 10.18805/LR-4181

Cite article:- Dutta Susanta, Singh Magan, Meena Kumar Rajesh, Onte Santosh, Basak Nirmalendu, Kumar Sanjeev, Meena V.K. (2021). Effect of Organic and Inorganic Nutrient Sources on Growth, Yield, Nutrient Uptake and Economics of Fodder Cowpea [Vigna unguiculata (L.) Walp.] . Legume Research. 44(9): 1046-1052. doi: 10.18805/LR-4181.
An experiment was conducted to evaluate the varying organic and inorganic nutrient sources on fodder cowpea [Vigna unguiculata (L.) Walp.] in the kharif of 2017 at ICAR- NDRI, Karnal. The result revealed that application of 100% RDF (N,P,K) along with biofertilizers (rhizobium, PSB, potassium and zinc solubilizer bacteria) (T6) gave significantly (P<0.05) higher in plant height (204.6 cm), primary branches (6.1), root length (24.47 cm), green matter yield (334.5 q ha-1), CGR (8.13 g m-2 day-1), RGR (4.68 g g-1 day-1), K content (1.45%) in plant, P uptake (23.01 kg ha-1) and K uptake (86.04 kg ha-1) and available Zn status (0.465 ppm) in soil, after harvesting of the crop. However, N content (2.93%) in plant, N uptake (172.51 kg ha-1) and Zn uptake (192.03 g ha-1) was maximum with the application of 66.67% RDF along with biofertilizers consortium (T7). Application of 100% RDF along with PSB (T3) recorded highest number of nodule (33), P content in plant (0.389%) and available P status (24.76 g ha-1) in soil, after harvest. Further studies that, available N status (208.03 kg h-1), K status (221.27 kg ha-1) in soil, after harvest and Zn content (33.31 ppm) in plant were significantly higher with these treatments like T8 -15 N, 60 P2O5, 40 K2O kg ha-1 along with rhizobium, T4 -100% RDF along with K solubilizer and T11 -FYM 5 t ha -1 with biofertilizers, respectively. In context of the economics of fodder cowpea production, highest gross return (Rs. 53525 ha-1) was obtained from T6 while maximum net return (Rs. 31351 ha-1) and benefit-cost ratio (1.45) were worked out maximum with the treatment T7.
The cowpea [Vigna unguiculata (L.) Walp.] is an annual herbaceous legume cultivated for its edible seeds, fodder as well as in green manuring for soil health improvement. It is an important kharif fodder due to its short duration, high yielding and quick growth along with high protein content and also palatable to ruminants (Singh et al., 2006) and the haulms are fed to animals as a nutritious feed. Farmers can also use this short duration pulse crop as a contingent crop during different climatic constraints. As it is a legume crop so it has the capacity to fix the atmospheric N into the soil by which it enhance the soil fertility. The inoculation of N2-fixing rhizobia bacteria is an economic and environmentally valuable option to provide N for plants. So far the symbiotic association of rhizobium with cowpea increases the yield and it may feasible alternative to replace, partially or totally of the mineral N fertilizers application (Farias et al., 2016). However, available phosphorus is also present only 0.1% of the total P in soluble form for plant uptake (Zhou et al., 1992) and its maximum portion is fixed into soil as an unavailable form. The use of biofertilizers containing P-solubilizing bacteria (Pseudomonas and Bacillus species) in agricultural soils avoid the fixation and considered as an environmental, eco-friendly alternative against chemical P fertilizers. Another primary mineral that is potassium also present only 2% in soluble form and 98% are insoluble and exist in the form of minerals like biotite, feldspar, mica, muscovite, vermiculite (Goldstein, 1994) in Indian soil. Potassium solubilizing bacteria Bacillus mucilaginosus has the potential to solubilize K mineral such as micas, illite and orthoclases through production and excretion of organic acids (Ullaman et al., 1996). More than 50% of Indian soils are deficient in zinc (Singh et al., 2005) and the major reason for the zinc deficiency is low solubility of zinc rather than total amount of zinc. Zn solubilizer bacteria increase the bioavailable Zn in rhizosphere soil (Whiting et al., 2001) and also enhancing the plant Zn content (Whiting et al., 2001; Biari et al., 2008). Biofertilizers in combination with RDF shows a significant increase in the uptake of the nutrients by the plant and the available nutrient in the soil (Puente et al., 2004). In addition, inoculation of rhizobium and PSB significantly increase the plant height and primary branches (Meena et al., 2015) and highest crop growth rate was also recorded by the combine application of organic and inorganic nutrient sources (Miheretu and Sarkodie-Addo, 2017).
Keeping in view the above facts the present research topic has been planned to study the “Effect of organic and inorganic nutrient sources on growth, yield, nutrient uptake and economics of fodder cowpea [Vigna unguiculata (L.) Walp.]”
The field experiment was conducted during kharif, 2017 at Research Farm of Agronomy Section, ICAR-National Dairy Research Institute, Karnal. The soil of the experimental field was clay loam in texture. Surface soil samples (0-15 cm) were collected randomly from the field before sowing and after harvesting of crop using soil augur and the composite sample was obtained by mixing them thoroughly. Representative samples were dried and made free from foreign materials by passing through 2 mm standard sieve. Some of the physicochemical properties of the experimental soil were : texture clay loam with sand- 43.59%, silt- 23.03% and clay- 33.28% (Bouyoucos, 1962); pH (1 : 2, soil : water)- 7.1, electrical conductivity (EC 1 : 2, soil : water)- 0.25 dSm-1 (Jackson, 1973); organic C- 0.61 % (Walkley and Black, 1934); available N- 175.6 kg ha-1 (Subbiah and Asija, 1956), available P- 20.8 kg ha-1 (Olsenet_al1954) and available K- 212.6 kg ha-1 (Jackson, 1967) and available Zn- 0.432 ppm was extracted by DTPA (Lindsay and Norvell, 1978). The experiment was laid out in randomized block design (RBD) with  twelve treatments viz., T1-Control (N0P0K0); T2-100% RDF (N20P60K40); T3-100% RDF+PSB; T4-100% RDF+ KSB; T5-100% RDF+ZnSB; T6-100% RDF+Rhizobium+ PSB+KSB+ZnSB; T7-66.67% RDF+Rhizobium +PSB+KSB+ ZnSB; T8-15 kg N+60 kg P2O5+40 kg K2O ha-1+Rhizobium; T9-10 kg N+60 kg P2O5+40 kg K2O ha-1 +Rhizobium; T10-60 kg P2O5+40 kg K2O ha-1+Rhizobium; T11-FYM (5 t ha-1) +Rhizobium+PSB+KSB+ZnSB; T12-FYM (10 t ha-1) and replicated by three times. The fodder cowpea variety C-152 was taken for assessment of different treatment effect on it because it has high foliage behavior than seed yielding capacity. Different inoculant like rhizobium, PSB, potassium solubilizer, zinc solubilizer were mixed with the molasses separately to make a slurry and then the required seeds of each treatment were mixed in their respective slurry so as to have uniform coating over the seeds and then shade dried for 30 minutes. The shade dried seed was sown within 24 hours. Treatment wise nitrogen, phosphorus and potassium was applied in the form of urea, SSP and MOP respectively as a basal application. Farm yard manure was applied before few days of sowing. Sowing was done in levelled plots at a row spacing of 30 cm and 40 kg ha-1 seed rate of cowpea variety C-152 was used. Observations on growth parameters like plant height, primary branches, crop growth rate, relative growth rate, root length, total root nodule and green fodder yield were recorded at the time of harvest. However, nitrogen content (Kjeldhal method), P, K, Zn content in plant (Bhargava and Raghupathi, 1993) and nutrient uptake by the plant were analyzed. Besides these, available N, P, K, Zn status after final harvesting of the crop were also analyzed to evaluate the nutrient available in soil, after harvesting. Finally, treatment wise gross return, net return as well as benefit-cost ratio on the basis of net profit were calculated in fodder cowpea production.
CGR (g m-2 day-1)
crop growth rate simply indicates the change in dry weight over a period of time. It was calculated by using following formula:

P= Area (m2) from which CGR was calculated.
T1= Time one (in days).
T2= Time two (in days).
W1= Dry weight at T1 time (in grams).
W2= Dry weight at T2 time (in grams).
RGR (g g-1 day-1)
Relative growth rate represents the logarithmic growth over a period of time. It is measured as the mass increase per aboveground biomass per day, for example as g g-1 d-1. It was computed by using following formula:

ln= Natural logarithm.
T1= Time one (in days).
T2= Time two (in days).
W1= Dry weight of plant at T1 time (in grams).
W2 = Dry weight of plant at T2 time (in grams).
Growth parameter
Data presented in Table 1 revealed that significantly higher plant height (204.6 cm) was observed when crop was fertilized with 100% RDF+Rhizobium+PSB+KSB+ZnSB (T6) which remained statistically at par with 66.67% RDF+Rhizobium+PSB+KSB+ZnSB (202.4 cm) (T7) and lowest value was found in control (162.1 cm). This result might be attributed that readily available nitrogen which is a major component of protoplasm helps in photosynthesis and boost up metabolic rate, cell division and cell elongation which, allow the plants grow faster (Tisdale et al., 1995).

Table 1: Effect of different nutrient sources on growth parameters and yield of fodder cowpea.

Whereas, number of primary branches of fodder cowpea was significantly higher (6.1) by the application of 100% RDF+Rhizobium+PSB+KSB+ZnSB (T6) presented in Table 1. However, it remained statistically at par with T7, T2, T8, T11, T3 and T9 and least number of primary branches (3.5)  was found in both T1 and T12. It might have happened due to increase in auxin with the high level of nitrogen supply brought about increase the branches per plant (Sharma and Dayal, 2005).
Different treatments had noticeable effect on root length of the fodder cowpea. It was observed that significantly higher root length (24.47 cm) was measured in treatment with 100% RDF+Rhizobium +PSB+KSB+ZnSB (T6). However, it remained statistically at par with T7, T8, T9, T11, T10, T3, T4 and T5 and these data are arranged in Table 1. Smaller root (20.93 cm) was measured under control treatment. These findings were in close conformity with that of Vaishnavi and Jeyakumar (2015). This might be due to the production of auxin and mineralization of nutrients by PGPR (Steenhoudt and Vanderleyden, 2000).
CGR increases rapidly when the crop develops, the leaf area expands and maximum CGR coincides with the early fruiting stage and decreases on maturity and RGR always decreases over time as the biomass of a plant increases. Data depicted in (Fig 1) that significantly higher CGR (8.13 g m-2 day-1) and RGR (4.68 g g-1 day-1) were registered under 100% RDF+Rhizobium+PSB+KSB+ZnSB (T6) and it remained statistically on par with T7, T8, T9, T3, T4, T5, T2 and T10, respectively. However, the lowest CGR (6.40 g m-2 day-1) and RGR (3.68 g g-1 day-1) were found under control treatment where any nutrient sources were not applied. The result might be attributed for Rhizobium inoculation which play a major role in synthesis of plant growth promoting hormones like auxin, cytokinin and gibberellins. The combined application of organic and inorganic nitrogen fertilizer to cowpea rather than single application of organic and inorganic nitrogen fertilizer leads to significant increase in plant growth and development. These results are in close conformity with the findings of Olusegun (2014).

Fig 1: Effect of different nutrient sources on crop growth rate (g m-2 day-1) and relative growth rate (g g-1 day-1) of fodder cowpea.abc values with different superscript within a column represent significant difference.

Yield attributes and yield
It was evident that significantly higher number of total root nodules (33.0) of fodder cowpea was recorded in treatment with 100% RDF+PSB (T3) which remained statistically on par with T6, T7, T2, T4 and T10 whereas, root nodule were least count (25.8) in control plot showed in Table 1. These results might be attributed that phosphorus solubilizer indirectly enhances the nodule numbers by providing more available P to the plants which is required for nodule formation (Heisinger, 1998). Integration of organic manure, inorganic fertilizer and bio-fertilizer application provide favorable aeration and moisture regime for better root growth and respiration and higher soil biological activity as compared to only inorganic fertilizers (Madhukewe et al., 2008).
Data presented in Table 1 obtained during the investigation revealed that 100% RDF+Rhizobium +PSB+KSB+ZnSB (T6) recorded significantly higher green fodder yield (334.5 q ha-1) which remained statistically at par with T7 (331.5 q ha-1). However, the lowest yield (196.9 q ha-1) was obtained from control treatment. The application of organic manures and bio-fertilizers has increased availability of nutrients that might have improved the growth attributes which enhanced the photosynthesis and translocation of carbohydrates to sink site which ultimately led to positive increase stover yields. This present findings were in line with the findings of Rhohit et al., (2013). Plants might have stimulated the rate of various physiological processes due to increased supply of nitrogen and their higher uptake by plants which led to increased growth and yield parameters and resulted in increased stover yields. These results are in close conformity with the findings of Patel et al., (2003), Singh et al., (2007) and Kumar et al., (2015a).
Nutrient content and uptake
Different treatments significantly influenced the N, P, K and Zn content and uptake on fodder cowpea production (Table 2). The application of treatment T7- 66.67% RDF+Rhizobium+PSB+KSB+ZnSB recorded significantly higher N concentration (2.93%) in fodder cowpea compared with rest of the treatments. Among the nutrient treatments (T2 to T12), only sole application of FYM (2.65%) failed to exert any significant effect on N content over control (2.63%). Significantly higher value of N uptake (172.51 kg ha-1) by fodder cowpea was recorded under the treatment T7 which remained at par with treatment Tover control (78.22 N kg ha-1). However, sole RDF (T2) and FYM applied treatment (T12) gave significantly lower value of N uptake (140.41 and 121.37 kg ha-1, respectively) as compared to integrated application of organic and inorganic nutrient. Rhizobium inoculation influences the nodulation which sustained greater supply of nitrogen to the crop. These results are supported by Lopes et al., (1996). The increased nitrogen content of stover with fertilizer application may be ascribed to greater availability of nitrogen and also for efficient absorption by the roots. These findings were in close conformity with Shivran and Ahlawat (2000).

Table 2: Effect of different treatments on nutrient content and nutrient uptake by fodder cowpea.

Nutrient applications showed significantly higher P content over control (0.319%). The application of treatment T3 (100% RDF+PSB) showed significantly higher P concentration (0.389%) which remained at par with the treatment T6, T7, Tand T2. The application of 100% RDF+Rhizobium+PSB+ KSB+ZnSB showed significantly higher uptake of P (23.01 kg ha-1) over rest of the treatments except treatment T7- 66.67% RDF+ Rhizobium+PSB+ KSB+ZnSB which recorded 22.61 kg P ha-1. Biofertilizers inoculation with PGPR in plants significantly increased the N and P content along with enhanced the uptake of essential nutrient by solubilizing the unavailable form and made available in the root zone. These findings were in close conformity with the Puente et al., (2004) and Kumar et al., (2015b).
More or less similar results to N uptake, statistically higher uptake of K (86.04 kg ha-1) was found under the application of treatment T6- 100% RDF+Rhizobium+PSB+ KSB+ZnSB over rest of the treatments. Whereas, significantly lower uptake of K was noticed under the sole application of RDF (T2) as well as FYM (T12) (60.41 and 55.23 kg K ha-1) in comparison to integrated nutrient treatments except control. Significantly higher K concentration (1.45%) in fodder cowpea was ascertained with the treatment T6- 100% RDF+Rhizobium+PSB+KSB +ZnSB over rest of the treatments except the treatment T4 (1.43%).
Significantly higher Zn concentration (33.31 ppm) in plant was found when fodder cowpea was fertilized with treatment T11-FYM 5 t ha-1+Rhizobium+PSB+KSB+ZnSB which remained at par with T5 (33.06 ppm) over rest of the treatments. The integrated fertilization of organic and inorganic nutrient sources exhibited significantly higher uptake of Zn over sole RDF (160.59 g Zn ha-1) as well as FYM (140.77 g Zn ha-1). Out of all the treatments, significantly higher Zn uptake (192.03 g ha-1) was confirmed under the treatment T7- 66.67% RDF+Rhizobium+PSB +KSB+ZnSB. Inoculation with PGPR enhanced the macro- and micronutrient uptake by plants may be due to their effect on initiation and development of lateral roots. This evidence supported by the findings of Rolfe et al., (1997). Higher NPK uptake was obtained may be due to the additive effects of combined inoculation of Rhizobium + PSB + PGRR (Prasad et al., 2002).
Soil nutrient status
Different treatments had significant effect on soil N status over control (Table 3). The application of treatment T8- 15 kg N+60 kg P2O5+40 kg K2O ha-1+Rhizobium recorded significantly higher soil N status (208.03 kg ha-1) over  rest of the treatments except T9 (207.59 kg ha-1).

Table 3: Effect of different treatments on the nutrient status of the soil after harvesting of cowpea.

Significantly higher P status (24.76 kg ha-1) of soil was recorded under the application of treatment T3- 100% RDF+microphos compared with remaining all the treatments.
Whereas, K status of soil was found to be significantly higher (221.27 kg ha-1) with treatment T4 - 100% RDF+KSB.
These results may be due to inoculation of biofertilizers enhanced soil fertility by solubilizing unavailable nitrogen, bound phosphorus and non-exchangeable potassium into available forms to the plant (Goud and Kale, 2010). The nutrient status of soil can be improved by the combine inoculation of Rhizobium, PSB and PGRR through their synergistic effect on nitrogen fixation. These findings were in close conformity with that of Pandey et al., (2015).
The application of treatment T6- 100% RDF+Rhizobium + PSB+KSB+ZnSB showed considerable higher Zn (0.465 ppm) status in soil and it remained statistically unaffected with the treatment T5 (0.460 ppm), T7 (0.460 ppm) and T8 (0.459 ppm). Zinc solubilizer (Pseudomonas fiuorescens) has the capacity to solubilize the insoluble zinc in the soil through the production of organic acids, like gluconic acids. This findings also supported by the work carried out by Di Simine et al., (1998).
The economics is of paramount importance for any crop production system. The maximum gross return was obtained under the treatment T6 (Rs. 53525 ha-1) closely followed by T7 (Rs.53045 ha-1), while least gross return was achieved from T1 (Rs.31499 ha-1). Maximum net return as well as B: C ratio was attained from treatment T7 (Rs. 31352 ha-1 and 1.45, respectively) followed by T6 (Rs. 30402 ha-1 and 1.31, respectively). Whereas, the lowest value of net return and B: C ratio was received from T1 (Rs. 12869 ha-1) and T12 (0.42), respectively.   
Best on the present investigation it can be inferred that application of 100% RDF+Rhizobium +PSB+KSB+ZnSB (T6) followed by 66.67% RDF+Rhizobium+PSB+KSB+ZnSB (T7) were found to be superior treatments with respect to growth, yield, nutrient uptake and economics of fodder cowpea.
The author are thankful to the Director, ICAR-National Dairy Research Institute, Karnal for his consistent support for providing the land and financial support in conducting the experiment which is the outcome of this manuscript.

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