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Soybean plays roles in reducing soil erosion, in biological nitrogen fixation, in pests and disease management and is also an important source of plant proteins. However production remains low in Malawi because of several factors, including the limited use or non-use of rhizobial inoculants and phosphorus fertilizers. Studies were conducted in 2011/12 and 2012/13 growing seasons in central Malawi to test the response of soybean to inoculation with biofix and soil amendments with phosphorus (P) fertilizer. The research used two approaches of research designed-research managed (RDRM) and research designed-farmer managed (RDFM) on-farm trials. The RDRM trials were laid in split plots replicated three times whereas RDFM trials were laid out on randomly selected farmers’ plots and field book was used to capture data. Analysis of variance was performed using Genstat (16th Edition) and Micro Soft excel. Results showed that inoculation significantly increased biomass yield, grain yield and nodulation. P-fertilizer did not have significant impact on grain yield. The yield in RDFM trials were generally lower than RDRM. The implications of the findings in smallholder farming systems in Malawi are discussed.
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Response soybean to inoculation with rhizobia and application of phosphorus fertilizers in Malawi
Chataika, B. Y. E.1*, Phiphira L.2
1International Centre for Tropical Agriculture (CIAT), Chitedze Research Station, P. O. Box 158, Lilongwe, Malawi
2International Institute for Tropical Agriculture (IITA), N2Africa Project, Chitedze Research Station, P. O. Box 30258, Lilongwe 3, Malawi
*Corresponding author. E-mail: [email protected]. Tel: +265 1 707 022/+265 8 88 894 595.
Outline of presentation
• Legumes and BNF
• Overview of the research Process
• Major Findings
• Conclusion and Recommendations
Legumes and biological nitrogen fixation
• BNF= atmospheric nitrogen biologically useful form.
• Root Nodules = factory for N-fixation to ammonia
• The symbiotic relationship (LxR) contribute largest amounts of fixed nitrogen to agriculture.
• Grain legumes contribute more than 20 million tons of fixed N to agriculture each year (Herridge et al. 2008).
• Nitrogen is the nutrient element most limiting to plant growth. • Replacement of soil nitrogen is generally accomplished by the
– 1. addition of N-fertilizers – 2. BNF.
Overview of the Research ProcessRDRM and RDFMAgronomy trials (RDRM Trials): Dedza, Lilongwe and Salima• Split plotsDelivery and Dissemination(RDFM Trials): Dedza, Lilongwe and Salima.• Identification and training of participants• Distribution of seed, biofix innoculant and fertilizer• Administration of field book
Field layout and Seed Inoculation
Inoculation Dedza Mitundu Msundwe Salima Mean
RH- 1442c 1444c 933a 1460c 1411
RH+ 2140d 2269d 1194b 2445e 2220
Site mean 1791 1857 1063 1952 1762
LSD<0.001(Site x Inoculation) = 147.8 CV = 18%
Grain yield response of soybeans to inoculation with biofix rhizobia across sites in 2011/12 growing season (kgha-1)
Grain yield response of soybeans to inoculation with biofix rhizobia across sites in 2012/13 growing season (kgha-1)
Inoculation Dedza Msundwe Salima Mean RH- 1887cd 867a 889a 1327
RH+ 2098d 1634c 1180b 1689
Site mean 1993 1251 1034 1508
LSD0.018 (Site x Inoculation) = 278
CV = 49.6%
• Biofix significantly increased grain yield in all the sites
• Inoculation with biofix increased grain yield by an average of 42% (57% in 2011/12 and 27% in 2012/13 seasons)
Dedza LL-Msundwe LL-Mitundu SALIMA0
500
1000
1500
2000
2500
3000
2106
1194
22672509
1428
933
1443 1465
RH+ RH-
Site/Environment
Gra
in y
ield
(kg/
ha)
Yield of soybean averaged over the two seasons across sites in RDRM
Soybean varietal response to inoculant in RDRM
Soybean varieties
Effect of biofix rhizobia on biomass (RDRM)
Putting Nitrogen to work for smallholder farmers in Africa
Effect of inoculants on nodulation (RDRM)
Dedza Mitundu Msundwe Salima0
1
2
3
4
5
6
RH+ RH-
Site
Nod
ule
scor
e
Effect of Inoculants and P-fertilizer on soybean grain yield (RDFM)
• The treatment with biofix inoculant produced the highest yield (1237kgha-1) which was significantly different from the control (661kgha-1) and phosphorus fertilizer treatment (672kgha-1).
• Seed treatment with biofix, led to an increase in grain yield by 87% as compared to the control.
No biofix, No P
No boifix, +P
With Biofix, No P
With Biofix & P
0
200
400
600
800
1000
1200
1400
661 672
1237 1132
Inoculant and P fertilizer
Yiel
d in
Kg
ha-1
An overview of financial impact of biofix on smallholder farmers
FactorFarmer Category
Grain Producer Seed ProducerBiofix requirement (g/ha) 400 400Cost of Biofix/ha 6.4 6.4Grain Yield without Biofix 661 661Grain Yield with Biofix 1237 1237Market price of produce* 0.5 1.75Total Revenue($) without Biofix 331 1157Total Revenue($) with Biofix 619 2165*1$=400MK Note: The table is very simplified for the purposes of highlighting the general picture
Conclusion and Recommendations• Our results demonstrated the consistent positive impact of using biofix
inoculants on grain yield of soybeans across the test sites.
• Un-inoculated treatment modulated in Dedza suggesting the presence of native rhizobia (though in low populations)
• Nodulation in Mitundu was heavily dependent of inoculant.
• We have also demonstrated that farmers’ productivity is far below potential even with the use of inoculants. Management could thus be another element that need to be enforced.
• We recommend further investigation on the presence of native rhizobia and survival rate of rhizobia in inoculated fields in soybean growing areas.
Acknowledgement• We acknowledge Bill and Melinda Gates Foundation
for funding this research.• We also acknowledge staff from the Department of
Agricultural Research Services for the support.
THANKS FOR YOUR TIME
