Soil Aggregation and Glomalin Quantification in Bamboo Species: At FRI, Dehradun

Soil aggregation is one of the most important factor in carbon sequestration (Understand the complete process). It is defined as the process whereby aggregates of various sizes join together by means of an array of organic and inorganic materials. The distribution of aggregates is differentiated between micro-aggregates (<250 µm) and macro-aggregates (>250 µm). Aggregates physically protect soil organic matter. It also influence microbial community structure, limits oxygen diffusion, determine nutrient adsorption and desorption and reduce run-off and erosion. Among the all microorganisms present in soil (soil biota), fungi are the most important agents involved in soil aggregation through fungal mycelia network, although roots and bacteria have a significant role as well.

Arbuscular Mycorrhizal Fungi (AMF) produces the glomalin, which helps to bind particles of soil together along with physical entanglement by the actual hyphae. Glomalin contain 30 to 40% carbon and can last for 40 years, it also forms aggregates that add structure to soil and keep other stored soil carbon from escaping.

Study area: The objective of this study was to quantify soil aggregates (Micro & Macro) and glomalin content in seven exotic bamboo species. The study area includes compartment no. 3 of the Bambusetum of the Forest Research Institute, Dehradun, where all the seven bamboo species – Dendrocalamus giganteus Munro, Bambusa  polymorpha Munro,  Bambusa  tulda Roxb.,  Bambusa  nutans Wall. Ex Munro, Bambusa multiplex (Lour) Schult., Cephalostachyum pergracile Munro and Melocanna baccifera (Roxb.) Kurz, are situated. Samplings were done in the month of April, 2010. Data of different characters of field survey were analyzed by One-Way ANOVA using Microsoft Excel. The difference between the treatments was tested at 5 percent level of significance.

Collection of Soil Sample/ Sample collection procedure

• Three soil samples from each culm (near the root area)of  the depth intervals of 0 to 30 cm were collected.
• Five samples from the same depth (as composite) had been collected from each site. This process is repeated in three directions of the bamboo culm (three replicates for each sample).
• Samples were placed in well labeled polythene bags with date and time.
• Samples were sieved by 2 mm mesh so as to remove the pebbles and gravel.
• Soil samples were stored in refrigerator to maintain the moisture content as it is necessary for microbial activity.
• Further soil samples were available for different analysis.

Soil Aggregation: Aggregate size distribution is to be determined using wet sieving with screen diameters of 0.25 mm and 0.053 mm.  The percent macroaggregates were higher than microaggregates in all the bamboo species except D. gigantius (Table.1 & Fig.1). Macroaggregates showed the overlapping trends over bamboo species while it was reasonably discrete in case of microaggregates. The maximum macroaggregate percentage was registered by B. tulda (48.90%) that was at par with C. pergracile (47.10%) and M. baccifera (47.73%). While minimum was recorded in D. gigantius (33.17%), which was significantly lower from all other species. Maximum microaggregate percentage was recorded in B. multiplex (40.02%) and minimum was registered in B. tulda (32.31%) that was significantly less than other bamboos. Microaggregate percentages of B. nutans (35.67%), C. pergracile (35.98%), D. gigantius (35.19%) and M. baccifera (35.35%) recorded at par values. Microaggregates for B. multiplex (40.02%) and B. polymorpha (39.93%) were also at par.

Table1. Aggregation properties of the soil collected from root zone of different exotic bamboos of FRI bambusetum

S. No.	Species	Macro aggregate (%)	Micro aggregate(%)
1.	Bambusa multiplex	40.13	40.02
2.	Bambusa nutans	45.13	35.67
3.	Bambusa polymorpha	40.48	39.93
4.	Bambusa tulda	48.90	32.31
5.	Cephalostachyum pergracile	47.10	35.98
6.	Dendrocalamus gigantius	33.17	35.19
7.	Melocanna baccifera	47.73	35.35
	Standard Error Mean	2.98	3.26
	Critical Difference (At 5% significance level)	2.48	2.59

Fig.1. Aggregation properties of the soil collected from root zone of different exotic bamboos of FRI bambusetum

Glomalin Content : Glomalin extraction is done by Total Protein Extraction method given by Wright and Upadhyaya, 1996 (Find more details here). Significant differences were recorded in the glomalin content among the exotic bamboo species (Table2 & Fig.2). The maximum value was recorded in C. pergracile (84.09µg/ml) and minimum was found in B. multiplex (48.24µg/ml).

Table2. Glomalin content of the soil collected from root zone of different exotic bamboos of FRI bambusetum

S. No.	Species	Spore count(µg/ml)
1.	Bambusa multiplex	48.24
2.	Bambusa nutans	73.76
3.	Bambusa polymorpha	69.86
4.	Bambusa tulda	59.08
5.	Cephalostachyum pergracile	84.09
6.	Dendrocalamus giganteus	62.97
7.	Melocanna baccifera	83.05
	Standard Error Mean	0.22
	Critical Difference (At 5% significance level)	0.67

Fig.2. Glomalin content of the soil collected from root zone of different exotic bamboos of FRI bambusetum

It is concluded that C. pergracile and M. baccifera are the two bamboo species among the seven which have the more capacity to sequester carbon than others (Maximum Glomalin quantity means higher Carbon content). This is only the one season study. Further research is needed to know the exact status of these bamboo species in carbon sequestration.

Reference

Mr Abhay Garg

E-mail: abhay_garg11[at]yahoo[dot]co[dot]in

Associated with: Dr. Y P Singh, Dr. Pawan Sharma , Solomon Das

Image Credit (Bamboo): www.123rf.com