Table 1.

Geographical, climatic and physicochemical soil characteristics of the two agro-ecological study regions in the eastern Mbeere and coastal Kilifi areas. Parameter ranges and if applicable averages of 15 cultivated and 5 uncultivated sites per region are listed. Composite soil samples were taken to a depth of 15 cm.

	Mbeere	Kilifi
Altitude (m a.s.l)	1049–1209	61–271
Agro-ecological zone	Lower midland	Costal lowland
Mean annual temp. (°C)	15–30	22–34
Mean rainfall (mm y−1)	640–1110	380–1230
Short rain	October–January	October–December
Long rain	March–June	April–July

Soil properties	Cultivated			Uncultivated			Cultivated			Uncultivated
	Mean	Min	Max	Mean	Min	Max	Mean	Min	Max	Mean	Min	Max
pH (H2O)	6.4	5.4	7.2	6.4	6.1	6.6	5.9	5.1	6.6	6.2	6.1	6.3
Total Na (g kg−1)	0.9	0.2	1.5	1.0	0.6	1.5	0.7	0.3	1.3	0.7	0.4	1.3
Organic Cb (g kg−1)	9.3	2.1	15.3	10.2	5.5	14.8	6.6	2.7	12.8	7.5	3.9	12.8
Pcres (mg kg−1)	4.03	0.88	28.19	1.38	1.09	2.18	2.49	0.92	17.50	4.36	0.57	18.04
Clayd (g kg−1)	171	96	256	197	129	329	337	96	696	372	96	675
Sandd (g kg−1)	680	504	804	628	404	764	471	144	904	520	145	884
Siltd (g kg−1)	149	60	300	175	107	267	192	0	440	108	20	180

^aTotal N: Kjeldahl method (Bremner, 1960).

^bOrganic C: (Walkley and Black, 1934).

^cPresin: P_i extracted with anion exchange resin membranes.

^dclay, sand and silt: hydrometer method (Bouyoucos, 1962).