http://www.ciat.cgiar.org/ipm/index.htm
Technical Resources, cassava, rice, etc
Sunday, February 11, 2007
Fertilizer response - Marginal rate of return - Nutrient balance calculation - Soil properties
R. J. Carsky1 and M. A. Toukourou2
(1)
International Institute of Tropical Agriculture, IITA-Benin, WARDA – Africa Rice Centre, B.P. 08–0932, Cotonou, Bénin
(2)
Institut National des Recherches Agricoles du Bénin, B.P. 01–884, Cotonou, Bénin
Received: 19 December 2003 Accepted: 29 July 2004
Abstract Market opportunities will drive intensification of cassava production and fertilizer will play a role in this. A trial was initiated on 15 farmers fields (replications) in one village territory in Benin on a relatively fertile sedimentary soil site to identify nutrients limiting cassava yield using nutrient omission plots over three cropping years. There was no response to fertilizer in the first year when fresh root yields in the unamended control averaged 19.1 t ha–1. In the second year, the control yield was 16 t ha–1 and there were significant reductions from withholding P (3.5 t ha–1) and K (2 t ha–1) from a complete fertilizer regime. Nutrient balance after 1 and 2 years (cumulative) showed substantial P and K deficits in unamended plots. In the third year, the control yield was 12.9 t ha–1 and effects of withholding K (5.3 t ha–1), P (5.0 t ha–1) and N (3.0 t ha–1) were statistically significant. Soil K was a significant source of variation in yield in the third year. In the third year of annual nutrient additions soil P and K in the top 0.3 m were increased by 37 and 40%, respectively. Based on the cumulative nutrient balance calculation, the annual application needed to compensate nutrient depletion was 13 kg N, 10 kg P, and 60 kg K ha–1. Partial budget analysis based on these amounts of fertilizer suggested that investment was clearly justified in the third year of continuous cropping at current low cassava prices.
(1)
International Institute of Tropical Agriculture, IITA-Benin, WARDA – Africa Rice Centre, B.P. 08–0932, Cotonou, Bénin
(2)
Institut National des Recherches Agricoles du Bénin, B.P. 01–884, Cotonou, Bénin
Received: 19 December 2003 Accepted: 29 July 2004
Abstract Market opportunities will drive intensification of cassava production and fertilizer will play a role in this. A trial was initiated on 15 farmers fields (replications) in one village territory in Benin on a relatively fertile sedimentary soil site to identify nutrients limiting cassava yield using nutrient omission plots over three cropping years. There was no response to fertilizer in the first year when fresh root yields in the unamended control averaged 19.1 t ha–1. In the second year, the control yield was 16 t ha–1 and there were significant reductions from withholding P (3.5 t ha–1) and K (2 t ha–1) from a complete fertilizer regime. Nutrient balance after 1 and 2 years (cumulative) showed substantial P and K deficits in unamended plots. In the third year, the control yield was 12.9 t ha–1 and effects of withholding K (5.3 t ha–1), P (5.0 t ha–1) and N (3.0 t ha–1) were statistically significant. Soil K was a significant source of variation in yield in the third year. In the third year of annual nutrient additions soil P and K in the top 0.3 m were increased by 37 and 40%, respectively. Based on the cumulative nutrient balance calculation, the annual application needed to compensate nutrient depletion was 13 kg N, 10 kg P, and 60 kg K ha–1. Partial budget analysis based on these amounts of fertilizer suggested that investment was clearly justified in the third year of continuous cropping at current low cassava prices.
Use of manure and plant density to boost yield
Titre du document / Document title
Effect of cassava mosaic disease, soil fertility, plant spacing and their interactions on cassava yields in Zanzibar
Auteur(s) / Author(s)
SPITTEL M. C. (1) ; VAN HUIS A. (2) ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) Plant Protection Service, PO Box 308, Chake-Chake, Pemba, Zanzibar, TANZANIE, REPUBLIQUE-UNIE DE(2) Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH Wageningen, PAYS-BAS
Résumé / Abstract
Cassava Mosaic Disease (CMD) and low soil fertility are limiting factors for the production of the preferred cassava variety Kibiriti mwekundu on the northern part of the island of Pemba in Zanzibar. Because CMD severity, assessed 7 months after planting in shifting cultivation fields at wide spacing of cassava (2.5 x 2.5 m), was always low, the hypothesis was tested whether damage due to CMD could be decreased by applying green manure. A total of 10 tonnes of fresh Gliricidia sepium leaves applied at 2 <1/2>, 4 and 5 <1/2> months after planting increased yield by 40 % to 7 tonnes per ha. The effect of green manure on yield was greatest on plants with highest CMD scores. The effect of plant density on CMD severity was also studied. Cassava yields at 1600, 2667, 6667 and 10 000 plants per ha and with soil of high fertility were 15, 17, 19 and 30 tonnes compared with 3, 6, 10 and 8 tonnes per ha respectively at a low fertility site. Under high soil fertility conditions, the CMD score was highest at close plant spacing, while under low soil fertility conditions there was no effect of spacing. Yield compensation occurred by plants neighbouring CMD affected plants, but only at the close plant spacing of 10 000 plants per ha and under high soil fertility conditions. Our results indicate that the impact of CMD on cassava can be reduced by applying green manure in fields with low soil fertility, that increasing organic matter content in the soil lowers CMD severity, and that CMD scores are reduced by increasing both soil fertility and plant spacing.
Revue / Journal Title
International journal of pest management (Int. j. pest manag.) ISSN 0967-0874
Source / Source
2000, vol. 46, no3, pp. 187-193 (17 ref.)
Effect of cassava mosaic disease, soil fertility, plant spacing and their interactions on cassava yields in Zanzibar
Auteur(s) / Author(s)
SPITTEL M. C. (1) ; VAN HUIS A. (2) ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) Plant Protection Service, PO Box 308, Chake-Chake, Pemba, Zanzibar, TANZANIE, REPUBLIQUE-UNIE DE(2) Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH Wageningen, PAYS-BAS
Résumé / Abstract
Cassava Mosaic Disease (CMD) and low soil fertility are limiting factors for the production of the preferred cassava variety Kibiriti mwekundu on the northern part of the island of Pemba in Zanzibar. Because CMD severity, assessed 7 months after planting in shifting cultivation fields at wide spacing of cassava (2.5 x 2.5 m), was always low, the hypothesis was tested whether damage due to CMD could be decreased by applying green manure. A total of 10 tonnes of fresh Gliricidia sepium leaves applied at 2 <1/2>, 4 and 5 <1/2> months after planting increased yield by 40 % to 7 tonnes per ha. The effect of green manure on yield was greatest on plants with highest CMD scores. The effect of plant density on CMD severity was also studied. Cassava yields at 1600, 2667, 6667 and 10 000 plants per ha and with soil of high fertility were 15, 17, 19 and 30 tonnes compared with 3, 6, 10 and 8 tonnes per ha respectively at a low fertility site. Under high soil fertility conditions, the CMD score was highest at close plant spacing, while under low soil fertility conditions there was no effect of spacing. Yield compensation occurred by plants neighbouring CMD affected plants, but only at the close plant spacing of 10 000 plants per ha and under high soil fertility conditions. Our results indicate that the impact of CMD on cassava can be reduced by applying green manure in fields with low soil fertility, that increasing organic matter content in the soil lowers CMD severity, and that CMD scores are reduced by increasing both soil fertility and plant spacing.
Revue / Journal Title
International journal of pest management (Int. j. pest manag.) ISSN 0967-0874
Source / Source
2000, vol. 46, no3, pp. 187-193 (17 ref.)
Sunday, February 4, 2007
TEMAS COMERCIALES
Feb 4/07
El remezón mundial del ethanol sigue... tanto como que los precios a los que subirá el maíz por fin permitirá acabar con buena parte de los subsidios agrícolas de EUA... y desde luego abre posibilidades de competencia de proveedores cercanos como México Lindo. http://www.washingtonpost.com/wp-dyn/content/article/2007/01/31/AR2007013100671_pf.html
El remezón mundial del ethanol sigue... tanto como que los precios a los que subirá el maíz por fin permitirá acabar con buena parte de los subsidios agrícolas de EUA... y desde luego abre posibilidades de competencia de proveedores cercanos como México Lindo. http://www.washingtonpost.com/wp-dyn/content/article/2007/01/31/AR2007013100671_pf.html
TEMAS AGROTECNICOS
Using the data provided by David Pimentel & T.W. Patzec [Nat.Resources Res Vol14, No.1, March, 2005, I have found: a) he underestimated the Corn Yield by 5% ;todays' average yield is 9.1 MT/ha. We ca use his ethanol yield from corn to be 502 L/ MT of Carbohydrates (CHOs). Corn in USA will yield 6.7 MT, CHOs/ha; Cassava(yuca) 3.6 MT, CHOs/ha. The yield of ethanol (ETOH) in USA is hence, 4481 L/ha. Mexico's corn will yield only 1271 L/ha. On the other hand using the tropical yuca: the yields of ETOH will be Colombia, 2151 L/ha, Costa Rica, 2863 L/ha, Mexico, 2863 L/ha. The last observation is quite illuminating. The yield of yuca in Mejico and Costa Rica [15 MT/ha] needs validation. According to the FAO, both countries produce some yuca, not as much as Colombia, but the yield is quite impressive.
The success of any ETOH operation in Mejico/Costa Rica hinges on producing yuca's CHOS at lower imput cost than the USA; less cost of labour, less machinery, less cost of fuel to distill the ETOH
The success of any ETOH operation in Mejico/Costa Rica hinges on producing yuca's CHOS at lower imput cost than the USA; less cost of labour, less machinery, less cost of fuel to distill the ETOH
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