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Evaluation of crop residues of North Gujarat
Biological Wastes 19 (1987) 227-231
Short Communication Evaluation of Crop Residues of North Gujarat
ABSTRACT The available quantities of residues of castor, pearl millet, mustard and potato were estimated on per hectare basis. Tensile strength and central load-bearing capacity of castor stem were measured to determine its usefulness in rural housing. The nutritive value of shells and leaves of castor, mustard straw and potato haulm were determined to assess their use as manure. The calorific value of stalk and shell of castor, stalk and straw of mustard and husk of pearl millet was also determined to study their fuel value. The study shows that the castor stalks may be utilised in rural housing. The castor shells and leaves, pearl millet husk, mustard straw and potato haulm are useful in composting and biogas generation. The calorific values of stalk and straw of mustard and castor stalks show their promise for direct burning.
INTRODUCTION Castor, mustard, potato and pearl millet are the major crops of the North Gujarat region of India. At present the castor and mustard stalks are used as fuel for cooking purposes by villagers. The other by-products--castor shell and leaf, potato haulm, mustard straw, pearl millet husk--are not fully utilized. There is wide scope to utilize these agricultural by-products for composting, as raw material for industries and for generating bio-energy which is useful in cooking, heating, lighting and pumping water for irrigation. Looking to these agricultural by-products, a study was conducted to find out the availability and potentiality of utilization of residues of various crops of North Gujarat. 227 Biological Wastes0269-7483/87/$03-50 © ElsevierApplied SciencePublishers Ltd, England, 1987. Printed in Great Britain
228
A. C. Varshney, K. L. Bhoi, B. P. Mehta
METHODS The stalks and shells of castor, pearl millet husk and mustard straw were collected from different fields of the Regional Research Station, Gujarat Agricultural University, Sardar Krishi Nagar, Gujarat. The potato haulms were allo.wed to dry in the sun on a field and the quantity obtained from a 5-hectare area was weighed. The available quantity of all these crop byproducts was computed on a per hectare basis. For estimating the quantity of castor leaves two-thirds of the leaves were defoliated from castor plants at the time of main spike initiation, because defoliation at this stage does not affect the yield (Anon., 1983). The leaves were weighed after drying in the sun. Samples of main stem and branch of castor plants were tested for tensile strength and central load-bearing capacity at LD Engineering College, Ahmedabad. Castor shells, mustard straw and mustard straw used as animal bedding material were composted separately in pits for four months. Samples were analysed for N P K value before and after composting. The potato haulm and castor leaf were also analysed for manurial value. Samples of pearl millet husk were mixed with water to give three concentrations of 2.5, 3.75 and 5% and were kept in bottles. An inoculum in the form of the digested slurry from a gobar (cowdung) gas plant was used in the proportion of 0-25, 0.50 and 0.751itre kg -~ husk. The solid concentration for mustard straw was taken as 3"5, 5"0 and 6.5% and inoculum quantity as 0-25, 0.5 and 0-75 litre k g - 1 for studying the trend of biogas generation at ambient temperature. The batch digestions were continued until gas production was negligible. The results given are averages from the three digestions of each substrate. Standard methods were used in all analyses and other determinations. The production of combustible gas was recorded by a water replacement method. The outgoing slurry was also analysed to measure the manurial value. The calorific value of stalks and shells of castor, stalk and straw of mustard and husk of pearl millet were determined for the assessment of their fuel value.
RESULTS A N D D I S C U S S I O N The available quantities of the agricultural by-products are presented in Table I. The data show that residues are available in considerable quantity to be used for various purposes.
229
Crop residues of Gujarat
TABLE i Quantity of By-products from Crops of North Gujarat Quantity (kg ha- t)
Crop residue
Mustard Stem Straw (after threshing) Castor Stem Shell Leaf Potato haulm (sun-dried) Pearl millet husk
370 1500 1900 750 780 350 320
The data of tensile strength and central load-bearing capacity of castor stalk (Table 2) show that the tensile strength of castor stalk is comparable with mild steel. The length of castor stalks varies from 63 to 166cm and the tapering is only 0"077% per metre. Thus there is good scope for the utilization of this material in rural housing as rafters. Nevertheless, processes for the protection against decay need to be determined which may require systematic research. However, the branches have poor strength and, therefore, are not suitable in rural housing. The values of nitrogen, phosphorus and potash show that the shell and leaf of castor, mustard straw and potato haulm have sufficient nutritive value to be used as manure (Table 3). It is clear from the data that the nitrogen and phosphorus, on a percentage basis, is greater after composting but this is due to the fact that the total weight of the material is reduced after composting. However, there was no significant change in the percentage of K20 because the samples were drawn from the middle and part of the potash might have got leached on the bottom of the pile. The data on calorific value show that mustard straw, mustard stalk and
TABLE 2
Tensile Strength and Central Load-bearing Capacity of Castor Stalk Material
Diameter (ram)
Tensile strength (kg cm - 2)
Diameter (mm)
Central load (kg) (span length 30 cm)
Stem Branch
25-20 13-80
300.50 100.30
23"10 14"80
125"00 45-00
A. C. Varshney. K. L. Bhoi. B. P. Mehta
230
TABLE 3
Manurial Value of Residues of Various Crops Composting in Pits for 4 Months
Ctmtponent ~?I mamo'c (%)
N P,O 5 K20
Castor shell
Mustard straw
Mustard straw used as bedding material
Potato haubn
Castor leaf
Bqfore After corncornposthtg posthtg
Before After corncornposting posting
Before After corncornposting posting
Before cornpost#zg
Before composting
1'33 0"79 --
2"73 1"47 --
0'53 0-77 1"07
0"91 0"98 0'91
0"33 0"74 0-68
0'60 1"05 0-85
0'69 0"97 0-59
1"06 1-32 0"74
castor stalk (Table 4) have sufficient fuel value for direct burning. The values are about 84 to 101% that of firewood. The laboratory study showed that 1 kg of pearl millet husk and mustard straw could generate 2501itre during 40 weeks and 182-01itre of biogas during 16 weeks, respectively. The methane percentage in gas and manurial value of outgoing slurry show a good promise for biogas generation from pearl millet husk and mustard straw (Table 5). TABLE 4
Heat Value of Different Crop Residues
Name o f crop b.v-products
Calorific t'alue (calg- ')
Castor stalk Castor shell Mustard straw Mustard stalk Pearl millet husk Firewood
4 767 3 665 4 034 3 948 3 626 4 708
TABLE 5
Quality of the Biogas and Digested Slurry Available from Pearl Millet Husk and Mustard Straw
Parameter
Pearl millet husk
Mustard straw
Methane in biogas (%) Digested slurry (%) N
60-65
55-65
0"8-1'0 0-45~)-70 0.75-1.80
1"10-1"80 0-70-1-30 0.50--0"75
P205 K,O
Crop residues of Gujarat
231
REFERENCE Anon. (1983). Research report of Regional Research Station presented in the 18th meeting of plant breeding genetics and plant physiology subcommittee of research council of Gujarat Agricultural University, Surat, India. A. C. Varshney, K. L. Bhoi & B. P. Mehta
Department of Rural Engineering, Gujarat Agricultural University, Sardar Kriski Nagar-385506. Gujarat, India (Received 17 February 1986; accepted 21 April 1986)
Short Communication Evaluation of Crop Residues of North Gujarat
ABSTRACT The available quantities of residues of castor, pearl millet, mustard and potato were estimated on per hectare basis. Tensile strength and central load-bearing capacity of castor stem were measured to determine its usefulness in rural housing. The nutritive value of shells and leaves of castor, mustard straw and potato haulm were determined to assess their use as manure. The calorific value of stalk and shell of castor, stalk and straw of mustard and husk of pearl millet was also determined to study their fuel value. The study shows that the castor stalks may be utilised in rural housing. The castor shells and leaves, pearl millet husk, mustard straw and potato haulm are useful in composting and biogas generation. The calorific values of stalk and straw of mustard and castor stalks show their promise for direct burning.
INTRODUCTION Castor, mustard, potato and pearl millet are the major crops of the North Gujarat region of India. At present the castor and mustard stalks are used as fuel for cooking purposes by villagers. The other by-products--castor shell and leaf, potato haulm, mustard straw, pearl millet husk--are not fully utilized. There is wide scope to utilize these agricultural by-products for composting, as raw material for industries and for generating bio-energy which is useful in cooking, heating, lighting and pumping water for irrigation. Looking to these agricultural by-products, a study was conducted to find out the availability and potentiality of utilization of residues of various crops of North Gujarat. 227 Biological Wastes0269-7483/87/$03-50 © ElsevierApplied SciencePublishers Ltd, England, 1987. Printed in Great Britain
228
A. C. Varshney, K. L. Bhoi, B. P. Mehta
METHODS The stalks and shells of castor, pearl millet husk and mustard straw were collected from different fields of the Regional Research Station, Gujarat Agricultural University, Sardar Krishi Nagar, Gujarat. The potato haulms were allo.wed to dry in the sun on a field and the quantity obtained from a 5-hectare area was weighed. The available quantity of all these crop byproducts was computed on a per hectare basis. For estimating the quantity of castor leaves two-thirds of the leaves were defoliated from castor plants at the time of main spike initiation, because defoliation at this stage does not affect the yield (Anon., 1983). The leaves were weighed after drying in the sun. Samples of main stem and branch of castor plants were tested for tensile strength and central load-bearing capacity at LD Engineering College, Ahmedabad. Castor shells, mustard straw and mustard straw used as animal bedding material were composted separately in pits for four months. Samples were analysed for N P K value before and after composting. The potato haulm and castor leaf were also analysed for manurial value. Samples of pearl millet husk were mixed with water to give three concentrations of 2.5, 3.75 and 5% and were kept in bottles. An inoculum in the form of the digested slurry from a gobar (cowdung) gas plant was used in the proportion of 0-25, 0.50 and 0.751itre kg -~ husk. The solid concentration for mustard straw was taken as 3"5, 5"0 and 6.5% and inoculum quantity as 0-25, 0.5 and 0-75 litre k g - 1 for studying the trend of biogas generation at ambient temperature. The batch digestions were continued until gas production was negligible. The results given are averages from the three digestions of each substrate. Standard methods were used in all analyses and other determinations. The production of combustible gas was recorded by a water replacement method. The outgoing slurry was also analysed to measure the manurial value. The calorific value of stalks and shells of castor, stalk and straw of mustard and husk of pearl millet were determined for the assessment of their fuel value.
RESULTS A N D D I S C U S S I O N The available quantities of the agricultural by-products are presented in Table I. The data show that residues are available in considerable quantity to be used for various purposes.
229
Crop residues of Gujarat
TABLE i Quantity of By-products from Crops of North Gujarat Quantity (kg ha- t)
Crop residue
Mustard Stem Straw (after threshing) Castor Stem Shell Leaf Potato haulm (sun-dried) Pearl millet husk
370 1500 1900 750 780 350 320
The data of tensile strength and central load-bearing capacity of castor stalk (Table 2) show that the tensile strength of castor stalk is comparable with mild steel. The length of castor stalks varies from 63 to 166cm and the tapering is only 0"077% per metre. Thus there is good scope for the utilization of this material in rural housing as rafters. Nevertheless, processes for the protection against decay need to be determined which may require systematic research. However, the branches have poor strength and, therefore, are not suitable in rural housing. The values of nitrogen, phosphorus and potash show that the shell and leaf of castor, mustard straw and potato haulm have sufficient nutritive value to be used as manure (Table 3). It is clear from the data that the nitrogen and phosphorus, on a percentage basis, is greater after composting but this is due to the fact that the total weight of the material is reduced after composting. However, there was no significant change in the percentage of K20 because the samples were drawn from the middle and part of the potash might have got leached on the bottom of the pile. The data on calorific value show that mustard straw, mustard stalk and
TABLE 2
Tensile Strength and Central Load-bearing Capacity of Castor Stalk Material
Diameter (ram)
Tensile strength (kg cm - 2)
Diameter (mm)
Central load (kg) (span length 30 cm)
Stem Branch
25-20 13-80
300.50 100.30
23"10 14"80
125"00 45-00
A. C. Varshney. K. L. Bhoi. B. P. Mehta
230
TABLE 3
Manurial Value of Residues of Various Crops Composting in Pits for 4 Months
Ctmtponent ~?I mamo'c (%)
N P,O 5 K20
Castor shell
Mustard straw
Mustard straw used as bedding material
Potato haubn
Castor leaf
Bqfore After corncornposthtg posthtg
Before After corncornposting posting
Before After corncornposting posting
Before cornpost#zg
Before composting
1'33 0"79 --
2"73 1"47 --
0'53 0-77 1"07
0"91 0"98 0'91
0"33 0"74 0-68
0'60 1"05 0-85
0'69 0"97 0-59
1"06 1-32 0"74
castor stalk (Table 4) have sufficient fuel value for direct burning. The values are about 84 to 101% that of firewood. The laboratory study showed that 1 kg of pearl millet husk and mustard straw could generate 2501itre during 40 weeks and 182-01itre of biogas during 16 weeks, respectively. The methane percentage in gas and manurial value of outgoing slurry show a good promise for biogas generation from pearl millet husk and mustard straw (Table 5). TABLE 4
Heat Value of Different Crop Residues
Name o f crop b.v-products
Calorific t'alue (calg- ')
Castor stalk Castor shell Mustard straw Mustard stalk Pearl millet husk Firewood
4 767 3 665 4 034 3 948 3 626 4 708
TABLE 5
Quality of the Biogas and Digested Slurry Available from Pearl Millet Husk and Mustard Straw
Parameter
Pearl millet husk
Mustard straw
Methane in biogas (%) Digested slurry (%) N
60-65
55-65
0"8-1'0 0-45~)-70 0.75-1.80
1"10-1"80 0-70-1-30 0.50--0"75
P205 K,O
Crop residues of Gujarat
231
REFERENCE Anon. (1983). Research report of Regional Research Station presented in the 18th meeting of plant breeding genetics and plant physiology subcommittee of research council of Gujarat Agricultural University, Surat, India. A. C. Varshney, K. L. Bhoi & B. P. Mehta
Department of Rural Engineering, Gujarat Agricultural University, Sardar Kriski Nagar-385506. Gujarat, India (Received 17 February 1986; accepted 21 April 1986)