000			021760000a22003250004500
904			_aBCO
905			_aC
908			_aJ
909			_aAS
914			_aFORES
082	0	4	_a40025
100	1		_992142 _aMAZZARINO, M.
100	1		_966131 _aEWEL, J.
100	1		_948342 _aBERISH, C.
100	1		_951399 _aBROWN, B.
260			_c1988
500			_a16ref. Sum.(En,Es)
520			_aThe effects of two treatments - natural succession and successional monoculture - on volcanic soil fertility following forest felling and vurning were studied over 5 yr in Costa Rica. For the successional monoculture maize (Zea mays), cassava (Manihot esculenta) and laurel(Cordia alliodora) were chosen. Owing to microvariability problems, each treatment was divided intro two groups of different fertility. Data on above-ground biomass and soil organic matter, total N, available P. percent acid saturation, extractable Ca, Mg, K and Al + H were analysed statistically. Percent acid saturation was considered a suitable index to evaluate tropical volcanic soil fertility (high saturation + high fertility) and vice versa. Defined in these terms, soil fertility was little affected by successional monoculture or natural succession when the original conditions of acid saturation were low (<2 percent at depth 0-5 cm. <20 percent at depth 5-25 cm). However, soil fertility was significantly affected when the original conditions were of high acid saturation (>7 percent at depth 0-5 cm. >50 percent at depth 5-25 cm); soil fertility was reduced under both successional monoculture and natural succession, but the reduction was less under the latter. A non-statistical comparison with a bare plot is also included
650	1	4	_9164829 _aSISTEMAS DE CULTIVO
650	1	4	_92064 _aCOSTA RICA
691			_9142769 _aCROPPING SYSTEMS
691			_aCOSTA RICA _92064
692			_aSYSTEME DE CULTURE
692			_aCOSTA RICA
773	0		_tTurrialba (Costa Rica) _d1988 _gv.38(4)p.345-351
040			_aCR-TuBCO _cCR-TuBCO _bEs
245	1	0	_aEfectos de una sucesión de cultivos en la fertilidad de suelos volcánicos respecto a la sucesión natural
942			_cANA
003			CR-TuBCO
999			_c54017 _d54017