Introduction
In the past, 19 years, maize (Zea mays L.) worldwide popularity was second after wheat and second most important food crop in Africa after cassava,1 but today maize is the top world staple food.2 In Kenya maize is the staple food for 80% of the society,3 the country is ranked third after Mexico and Malawi with per capita consumption of 125 kg.4
Maize yields in Kenya have been considerably low on average 2t/ha against a potential production of 6t/ha.5 This is due to various constraints which include a biotic ones such as lack or low farm inputs, and weather conditions and biotic ones such as weeds, insect pests, arthropods, diseases. Among the biotic factors weeds are the major constraints with crop yield losses estimated on average 80% depending on weed species.6
Conventional tillage method most commonly used by peasant farmers to control weeds in maize production is hand weeding which is tedious, drudgery and inefficient.7 The critical period of weed competition in maize is 2-6 weeks after crop emergence and maize also requires a minimum of three weedings to keep weeds at threshold for maximum yield.
Weeding accounts for 60% of time the peasant farmer spends in farming and saving this time means the farmer can engage in other profitable income generating activities according to.8 The same authors also noted that use of conventional tillage has reduced maize crop yields and profitability, increased the costs of production due to use of more fertilizer and fuel to plough the land and is also responsible for soil degradation. According to,9 use of glyphosate and lasso in no till system reduced cost of production by 50% compared to conventional tillage. The aim of the study was to compare the effectiveness of glyphosate ( zero tillage ) with that of hand weeding (conventional tillage) on weed management in maize production.
Material and Methods
The study was carried out in Kigumo District in Central province of Kenya, the trial site was about 115 km in a North West direction from Nairobi and lies at an altitude of about 1800m above sea level and traversed by longitude 360 59’E and latitude 00 41.7’S. The experiment was arranged in a randomized complete block design (RCBD) with the main plot containing two maize varieties namely DK8031 and DUMA SC 41. The subplots consisted of three weed management practices namely hand weeding three times, glyphosate applied three times and no tillage (control). The treatment combinations were replicated three times and repeated for two seasons (long and short rains). The plot size was 5 x 3 m, with maize planted at a spacing of 75 cm between and 30 cm within rows. Planting holes were prepared at 5cm depth and 20g/hole (200kg/ha) of NPK (23:23:0) fertilizer was applied and thoroughly mixed with soil before planting two seeds and covering with soil. Glyphosate (36% EC a.i) treated plots were sprayed using a 15 litre knapsack sprayer at 1.0 5 kg /cm2 five days prior to maize planting and repeated (directed spray) at 3WAP (3weeks after planting), 7WAP and 11 WAP. Conventional tillage was achieved by hand hoeing before planting followed by hand weeding three times at 3WAP, 7WAP and 11 WAP. Under no tillage practice, maize was planted after hand hoeing but no weeding was done until crop maturity. Data was collected in a net area of 3 by 1.5 m at the centre of each plot. Percentage maize germination and vigour, weed count by species, fresh and dry weed biomass, plant height and maize grain yield were recorded. Data was analyzed using Gen Stat computer software package. ANOVA was used to assess treatment effects at p< 0.05. Treatment means were separated by Student Newman Keuls.
Results
During the trials rainfall distribution was poor leading to fair and poor crop performance for the long and short rain seasons respectively (Table 1).
Table 1: Kigumo District Rainfall Data (Mm) During The Year 2009.
Month | Year 2009 | Year 2010 | ||
Rainfall amount(mm) | Number of wet days | Rainfall amount (mm) | Number of wet days | |
JAN | 12 | 4 | 162 | 11 |
FEB | 33 | 3 | 18.4 | 11 |
MAR | 37.2 | 8 | 233.5 | 18 |
APR | 175 | 15 | 280.6 | 25 |
MAY | 445.5 | 26 | 280.6 | 25 |
JUNE | 11 | 66 | 176.9 | 13 |
JULY | 7 | 5 | 24.7 | 8 |
AUG | 22.5 | 8 | 112 | 16 |
SEPT | 46 | 9 | 24.5 | 11 |
OCT | 380.5 | 19 | 250.6 | 15 |
NOV | 216 | 15 | 148.2 | 13 |
DEC | 305 | 21 | 0 | 0 |
TOTAL | 1691 | 199 | 1712 | 166 |
Legend for Table 1 : + Source: Ministry of Agriculture Kigumo district Kenya
Maize planted under zero tillage, using glyphosate and that planted under conventional tillage did not differ significantly (p > 0.05) in terms of percent germination, vigour and weed count(p > 0.05) during the long rainy season. However there were significant differences (p < 0.05) between zero and conventional tillage practices in the number of weed species during the short rain season (Table 2). There were more biomass of broad leaf weed species followed by grasses then sedges irrespective of maize variety and weed management practice (Table 3). Under each maize variety, glyphosate and hand weeding had equal and significantly lower biomass of grasses, broadleaf and sedges compared to no tillage weed management practice (P < 0.05) (Table 3). In both long and short rain seasons the two tillage practices did not significantly differ in terms of maize grain yield for the two maize varieties (P <0.05) although each of the varieties under glyphosate had higher grain yield than under hand weeding in both seasons (Table 4).
Table 2: Average Weed Counts/4.5m2 During The Short Rains Season 2010.
Maize variety | Weed management | Weed counts/4.5m2 | Average | ||||
1st 3WAP | 2nd 7WAP | 3rd 11WAP | 4th 15WAP | 5th 19WAP | |||
DUMA SC 41 | Glyphosate | 29.1a | 15.1a | 3.3a | 7.7a | 10.7a | 13.2 |
No tillage | 39.5a | 35.9b | 37.1c | 44.6c | 40.1c | 39.4 | |
Hand weeding | 29.1a | 15.5a | 16.4b | 22.1b | 24.6ab | 21.5 | |
DK8031 | Glyphosate | 23.3a | 11.3a | 2.8a | 6.1a | 7.0a | 10.1 |
No tillage | 38.3a | 27.9a | 29.3c | 31.2b | 27.1b | 30.8 | |
Hand weeding | 23.7a | 9.8a | 14.3b | 19.9b | 19.5ab | 17.4 | |
Lsd | 29.50 | 18.29 | 11.32 | 13.66 | 12.23 | ||
CV% | 59.60 | 61.90 | 62.30 | 35.00 | 39.40 |
Legend for Table 2: In the table means bearing the same letter are not significantly different along the columns
Table 3: Dry Weight (G) Weed Biomass For Both Long And Short Rain Seasons.
Maize variety | Weed management | Long rains (2010) | Short rains (2010) | Average | ||||
Weed category | Weed category | |||||||
Broad Leaf | Grasses | Sedge | Broad Leaf | Grasses | Sedge | |||
DUMA SC41 | Glyphosate | 432ab | 174b | 0.65a | 141a | 109a | 0.1a | 142.8 |
No tillage | 1371b | 2504d | 4.47a | 1262b | 3090c | 9.8a | 1373.6 | |
Hand weeding | 600ab | 431c | 2.5a | 74a | 35.7a | 1.8a | 190.8 | |
DK8031 | Glyphosate | 271a | 62a | 0.41a | 134a | 3.6a | 0.6a | 78.6 |
No tillage | 980ab | 277b | 6.3a | 1268b | 1890b | 13.5ab | 739.1 | |
Hand weeding | 493 ab | 144a | 4.2a | 22a | 28.1a | 5.3a | 116.1 | |
Lsd | 631.6 | 103.2 | 9.302 | 675.6 | 619.2 | 10.05 | ||
CV% | 57.9 | 1011.5 | 139.5 | 105.2 | 54.7 | 133.2 |
Legend for Table 3: In the table means bearing the same letter are not significantly different along the columns
Table 4: Duma Sc41 And Dk8031 Maize Grain Yield (T/Ha) For Both Long And Short Rain Seasons.
Maize variety | Weed management | Long rains | Short rains | Average |
DUMA SC41 | Glyphosate | 1.01a | 0.87a | 0.94 |
No tillage | 0.40a | 0.08a | 0.24 | |
Hand weeding | 0.73a | 0.85a | 0.79 | |
DK8031 | Glyphosate | 2.19a | 1.37a | 1.78 |
No tillage | 1.14a | 0.36a | 0.75 | |
Hand weeding | 1.65a | 1.36a | 1.51 | |
Lsd | 1.48 | 1.39 | ||
CV% | 58.4 | 77.4 |
Legend for Table 4: In the table means bearing the same letter are not significantly different along the columns
Discussion
The study showed there were no significant differences in percentage germination and crop vigour between the two tillage practices, the two maize varieties in both seasons. The results of the three weed counts done at 11, 15 and 19 weeks after planting (WAP), showed that there were significant differences in number of weed species between glyphosate (zero tillage) and those of hand weeding (conventional tillage).Glyphosate was more effective in suppressing the weeds than hand weeding.
The weed biomass for the two tillage practices were not significantly different but hand weeding (conventional tillage) had higher weed biomass compared with glyphosate (zero tillage). This conforms to findings by 10 that although glyphosate (zero tillage) effectively suppressed weeds than hand hoeing at 3 WAP in the absence of weeding, at harvest the weed populations and weed dry matter on zero-tillage were similar to the hand hoe treatment.
The tillage practices were found to have significant effect on plant height where DK8031 variety under glyphosate (zero tillage) average plant height was 1.89 m while under hand weeding (conventional tillage) the average plant height was 1.69 m. DUMA SC 41 variety under glyphosate (zero tillage) the average plant height was 1.42 m while under hand weeding (conventional tillage) it was 1.30 m. These results conform to those of 11 who reported that reduced tillage produced maximum height of 198.6 cm while hand weeding (conventional tillage) produced maximum height of 192.6cm indicating that tillage practices had significant effect on plant height. There was no significant difference between the two tillage practices in number of cobs per plant, average cob weight and mean grain yield of the maize varieties in both seasons although glyphosate had higher grain yield than hand weeding in both seasons. There were significant differences between the two maize varieties in grain yield (tones /ha). DK8031 had significantly higher grain yield than DUMA SC41. Better performance of glyphosate could be due to lack of soil disturbance in zero tillage which creates a favourable environmental conditions for buried weed seeds germination by exposing them on to the soil surface. This is in agreement with 12 who found that use of herbicides in weed management in maize production resulted into higher yields under zero tillage than under hand weeding (conventional tillage).
Tillage had no effect on crop percentage germination and vigour at 5 WAP. Glyphosate was more effective in weed suppression than hand weeding. Tillage practices had effect on maize plant height but none on number of cobs per plant, average cob weight and dry grain yield. Glyphosate was found to be more suitable for use in weed management than hand weeding for soil and water conservation purposes and saving time taken in hand weeding while DK 8031 variety was suitable for use in agro-ecological zone UM 1 than DUMA SC 41 variety.
Acknowledgements
First I would like to thank ASARECA for financial support through Hottentiah W. Mwangi (Mrs) and Dr.Z.M.Kinyua sponsored projects, secondly I wish to express my gratitude to Kenya Agricultural Research Institute and the University of Nairobi for their infrastructural support during the project execution.
Refrence
- FAO,(1992). Maize in human nutrition file://F:\maize origin.htm
- Mulaa,M.M.,Bergvinson,D.J.,Mugo,S.N.,Wanyama,J.M.,Tende,R.M.,DeGroote, H. and Tefera,T.M., ( 2011). Evaluation of Stem borer resistance, Management strategies for Bt maize in Kenya based alternative host refugia.
- Michael, N.N., (1989). Experiences in weed control problems in maize (Zea mays L.) seed production in the Trans-Nzoia District of Kenya.In 12th, Biennial conference of weed Science Society for Eastern Africa.
- Pingali, P. L., (2001).CIMMYT 1999-2000:World Maize Facts and Trends.Meeting world maize.
- Export processing zones authority (EPZA), (2005). Grain production in Kenya
- SPitters,C.J.T., Kropff,M.J., and Groot, dew, (1989). Competition between maize and Echinocloa crus-galli.
- Chui, J.N;Kusewa,T.M; and Kabumbura, J.M; (1996).Use of cultural practices, physical and chemical methods on weed control in maize and bean cropping systems. In Sutherland, J.A; (1999). Towards increased demand driven technology (KARI/DFID NARP II Project) end of project conference. Nairobi Kenya.
- Cereal knowledge bank, IRRI and CIMMYT, (2007). Are reduced tillage practices suitable for growing maize? knowledge bankirr.org/ckb/index.php/agronomy (accessed on 29.10.2010)
- NRIL and KARI, (2005). Improved access to appropriate farm inputs for integrated maize crop management by small scale farmers in Embu and Kirinyaga districts in Kenya.
- Kombiok J.M., Alhassan A.Y. (2007). Tillage effects on subsequent weed types, population and biomass in maize cropped in Northern savanna zone of Ghana. In Journal f sustainable Agri. Vol 30. Issue 1, pp. 47-57
CrossRef - Hamid, N; Mohammad, A. J;, Mehran, G. and Mohammad, A. R., (2007). Influence of tillage practices on the grain yield of Maize and some soil properties in Maize – Wheat cropping system of Iran. Journal of Agriculture and Social Sciences 1813-2235/2007/03- 3-87-90
- Aune, J.B.,Teklehaimot, R.D.A., and Bune, B.T., ( 2000 ). Zero tillage or reduced tillage demonstration plots of Sasakawa (Global in 2000) in farmers’ fields in 1999 and 2000, using herbicides to control weeds showed that yields were higher under reduced than under conventional tillage