Contribution of Jatropha curcas to soil quality improvement in a degraded Indian entisol

Figures & data

Table I. Description of selected treatments (Jatropha Experimental Farm, Chorvadla).

Treatment Name	Treatment description	Rates of organic/Inorganic amendment
BBA	Native vegetation site adjacent to experimental area on which Zizyphus mauritiana is the predominant plant	-NIL-
NPO	Control plot, cultivated to Jatropha with no amendment	-NIL-
NPI	Phosphorus amended plot, cultivated to Jatropha. Jatropha cake and single super phosphate (SSP) are the amendments	Jatropha cake at 2.25t ha^−1. SSP at 62 kg ha^−1
NIP	Nitrogen amended plot, cultivated to Jatropha. Jatropha cake and urea are amendments	Jatropha cake at 2.25t ha^−1. Urea at 65 Kg ha^−1.
NIPI	Nitrogen + Phosphorus amended plot, cultivated to Jatropha. Jatropha cake and SSP are amendments	Jatropha cake at 2.25t ha^−1. Urea at 65 kg ha^−1. SSP at 62 kg ha^−1.
NIIP	High nitrogen amended plot, cultivated to Jatropha. Jatropha cake and urea are amendments	Jatropha cake at 2.25t ha^−1, Urea at98 kg ha^−1

Table II. Dry aggregate fraction, particle size distribution and mean weight diameter as influenced by Jatropha cultivation at Chorvadla, western India.

Treatment	2–0.25 mm. (macro-aggregates)	0.25–0.053 mm (micro-aggregates)	>0.053 mm (silt and clay)	Mean weight diameter (mm)	Clay	Silt	Sand
BBA	0.62ab	0.41	0.023b	0.68b	11.3b	31.8a	52.5d
NPO	0.72a	0.26	0.017b	0.84a	9.6b	20.2c	68.3a
NPI	0.58b	0.38	0.017b	0.71b	15.1a	30.6a	53.9cd
NIP	0.64ab	0.33	0.02b	0.77ab	13.7ab	22.6bc	63.0ab
NIPI	0.57b	0.44	0.09a	0.68b	13.4ab	30.5ab	55.5bcd
NIIP	0.65ab	0.31	0.02b	0.79a	11.5b	25.8abc	61.6abc
LSD (0.05)	0.101	0.125	0.047	0.103	0.612	0.30	0.156
Significance	*	NS	*	*	*	*	*
Values within the same column having same letter are similar. *Siginificant at p<0.05

Table III. Water stable dry aggregate fraction and aggregate silt and clay (ASC) as influenced by Jatropha cultivation at Chorvadla, western India.

	Macro-aggregate			Micro-aggregate
Treatments	2–250 mm	0.25–0.053 mm	<0.053 mm	0.25–0.053 mm	<0.053 mm	ASC
BBA	0.52ab	0.29a	0.19ab	0.82	0.18	3.91a
NPO	0.68a	0.17b	0.15b	0.83	0.17	3.30b
NPI	0.47b	0.28ab	0.25a	0.79	0.21	3.99a
NIP	0.50ab	0.30a	0.20ab	0.77	0.23	3.49a
NIPI	0.52ab	0.27ab	0.21ab	0.78	0.232	3.93a
NIIP	0.55ab	0.25ab	0.20ab	0.80	0.20	3.72ab
LSD (0.05)	0.166	0.1143	0.096	0.081	0.081	0.152
Significance	*	*	*	NS	NS	*
Values within the same column having same letter are similar. *Siginificant at p<0.05

Table IV. Carbon and nitrogen concentrations (g kg⁻¹) of whole soil and water stable aggregates as influenced by Jatropha cultivation at Chorvadala, western India.

Treatments	BBA	NPO	NPI	NIP	NIPI	NIIP	LSD (0.05)	Significance
Whole soil Carbon	5.06	9.55	5.33	4.19	5.96	4.50	3.29	NS
Nitrogen	1.17ab	1.56a	0.72b	1.04ab	1.04ab	0.70	0.29	*
C: N	4.36	6.12	7.50	4.11	6.04	7.06	2.98
Macro (2–0.25 mm) aggregates								NS
C	10.19	10.79	4.78	8.77	5.38	7.26	2.665	NS
N	1.02a	1.19a	0.73ab	1.14a	0.48b	0.73ab	0.343	*
Micro (in macro-aggregates) aggregates
C	2.20b	4.47ab	7.03a	4.64ab	3.73ab	4.17ab	2.702	*
N	0.69ab	1.44a	0.86ab	0.68ab	0.60b	0.96ab	0.484	*
Micro (0.25–0.053 mm) aggregates
C	4.92b	9.18a	4.36b	6.01ab	3.96b	4.66b	1.676	*
N	0.45b	1.24a	0.40b	0.53b	0.43b	0.39b	0.463	*
Values within the same row, having the same letter are similar. *Siginificant at p<0.05

Table V. Relationship between mean weight diameter (MWD, mm), dry macro-aggregates, whole soil and micro-aggregate associated carbon and nitrogen.

Variables
Dependent	Independent	Equation	R^2*	P level**
MWD	Dry macro-aggregate fraction	Y=0.09 + 1.04 X	0.822	<0.001
MWD	Whole soil organic carbon	Y=0.64 + 0.016 X	0.23	0.025
MWD	C/N ratio	Y=0.697 + 0.007 X	0.102	0.101
MWD	Water stable micro-aggregate associated organic carbon	Y=0.58 + 0.029 X	0.505	<0.001
MWD	Water stable micro-aggregate associated nitrogen	Y=0.63 + 0.13 X	0.422	0.002
Dry macroaggregate fraction	Whole soil organic carbon	Y=0.54 + 0.014 X	0.214	0.03
Dry macroaggregate fraction	Water stable micro-aggregate associated organic carbon	Y=0.49 + 0.025	0.509	<0.001
Dry macroaggregate fraction	Water stable micro-aggregate associated nitrogen	Y=0.53 + 0.113 X	0.407	0.003
*Coefficient of correlation. **Level of significance of coefficient of correlation.