000			03229nam a22004697a 4500
001			G74501
003			MX-TxCIM
005			20211006084815.0
008			121211s ||||f| 0 p|p||0|| |
020			_a92-9146-065-6
040			_aMX-TxCIM
072		0	_aP33
072		0	_aP35
082	0	4	_a633.15 _bEAS No. 6
100	1		_aIkerra, S. _uMaize Production Technology for the Future: Challenges and Opportunities. Proceedings of the Eastern and Southern Africa Regional Maize Conference, 6; Addis Ababa (Ethiopia); 21-25 Sep 1998
110	2		_aCentro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), Mexico DF (Mexico)
245	0	0	_aSoil nitrogen dynamics and maize yields in a Gliricidia Sepium-maize intercrop in Southern Malawi
260			_aAddis Ababa (Ethiopia) _bCIMMYT|EARO : _c1999
300			_ap. 226-231
340			_aPrinted
520			_aMany soils of southern Africa are severely deficient in N, but inorganic fertilizers are frequently unaffordable for most farmers. Leguminous fallows or intercrops can alleviate N deficiency, but N use efficiency of organic inputs may be low due to non-synchrony of N release and crop N requirements. We monitored soil inorganic N dynamics for two seasons in a gliricidia [Gliricidia sepium (Jacq.) Walp.]- maize (Zea mays L.) intercrop in the unimodal rainfall area of southern Malawi. Treatments were plus or minus gliricidia, and N at 0, 24 or 48 kg N ha-1 in factorial combination. Application of gliricidia prunings significantly (p < 0.001) increased topsoil (0-20 cm) inorganic N at the end of the dry season. Fertilization alone also increased topsoil N (p < 0.001 ), but accumulated 38 to 41% less N than the tree plots. Differences between tree and fertilized plots became non-significant by 4 weeks after planting. Tree plots accumulated significantly (p < 0.01) more ammonium-N during the dry season. Nitrate-N remained constant during the dry season but rose rapidly in tree plots after the onset of rains. Both tree biomass and inorganic N significantly (p < 0.001) increased maize grain yields. Pre-season inorganic N accounted for 71% of the variation in maize yields for the two seasons data combined. A 2- factor model including pre-season inorganic N and anaerobic N mineralization potential accounted for 84% of the variability in maize yields for the two seasons data combined, Pre-season inorganic N could be used to adjust or eliminate basal applications of N in seasonal rainfall areas, particularly in seasons preceded by a drought year. Delayed timing of biomass additions may increase N use efficiency by the crop.
546			_aEnglish
591			_a0103|AL-Maize Program|AGRIS 0102|AJ
595			_aCPC
650	1	0	_aAfrica
650	1	0	_aGliricidia sepium
650	1	0	_aInorganic fertilizers
650	1	0	_aIntercropping
650	1	0	_91963 _aLegumes _gAGROVOC
650	1	7	_aMaize _gAGROVOC _2 _91173
650	1	0	_aMalawi
650	1	0	_aMineralization
650	1	0	_aNitrates
650	1	0	_aNitrogen
653	0		_aCIMMYT
650	1	0	_91314 _aZea mays _gAGROVOC
700	1		_aBuresh, R.J., _ecoaut. _92061
700	1		_aCIMMYT
700	1		_aMaghembe, J.A., _ecoaut.
700	1		_aSmithson, P. C., _ecoaut.
942			_cPRO
999			_c10029 _d10029