Availability and Conditions of Agricultural Machinery in Public and Private Sectors of Borno State, Nigeria Arid Zone Journal of Engineering, Technology and Environment. October, 2007; Vol.5, 54-59 Copyright© Faculty of Engineering, University of Maiduguri, Nigeria. Print ISSN: 1596-2644, Electronic ISSN: 2545-5818 www.azojete.com.ng EFFECTS OF TILLAGE TREATMENTS ON WEED CONTROL IN A MAIZE FIELD ON SANDY LOAM SOIL OF NORTH EASTERN NIGERIA Kawuyo, U.A.1, M. A. Haque1 and A.M. Usman1 Abstract This study was carried out to determine the effects of tillage treatments; namely: zero-tillage (T1), disc ploughing (T2), disc harrowing (T3) and disc ploughing followed by disc harrowing (T4) on weed control in a maize field. Plant height (cm), weed density (No/m2) and fresh weed weight i.e. weed biomass (g/m2) were measured at various growth stages of the crop, while grain yield (Kg/ha) was determined after harvest. The study was conducted in 1999 and 2000 farming seasons. The results showed that there were significant differences between tillage treatments for all the measured parameters in both years. The grain yield increased by 34and 36% for the year 1999 and 2000 respectively when treatments T1 and T4 were compared. A reduction in weed density at harvest by 57 and 52% in 1999 and 2000 respectively was obtained when treatments T1 and T4 were compared. Also, there was a 53 and 34% reduction in 1999 and 2000 respectively for the weed biomass when these two treatments were compared. It was recommended that treatment T4 be adapted for better weed control. 1. Introduction Tillage in agriculture is defined as the mechanical manipulation of soil to provide conditions suitable for the growth of crops, control of weeds, maintenance of infiltration capacity and aeration (Farral and Basselman, 1979; ASAE, 1993). Reasons for tilling the soil have also been given by many authors and these include seedbed preparation, weed control, improvement of soil physical conditions, management of plant residues, minimizing soil erosion, incorporation f fertilizers and to improve productivity (Foth 1978; Kepner et al. 1978 and Ohu, 1995). In agriculture, a weed is any plant growing in a place not meant for it. This may be herbaceous or woody, creeping or erect. Almost any kind of plant can, therefore, be a weed as long as it exists in a location or situation where it is considered undesirable. Weed is certainly a major nuisance for farmers. In any crop production, weed is one of the major factors affecting crop yield. This is due to competition for a number of vital resources such as light, water and nutrients (Anonymous, 1987). According to Rouanet (1987), maize needs to be weeded two or three times (for optimal yield). First, at the plantlet stage, that is, 10-15 days after emergence; secondly, at the start of booting, and thirdly, before harvesting to facilitate harvesting operations. He further reported that, weeding by hoe at three and seven weeks after planting is required for optimum yield. If herbicide is used, Primextra, a pre-emergence herbicide (5L/ha) should be applied within two days after planting (DAP) in the case of conventional tillage. For strip tillage, Primextra (5L/ha) plus Gramaxone (4 L/ha) should be used (Rouanet, 1987). Data from many experiments support the conclusions that the major reason for cultivation is weed control. It was reported by Matasova et al. (1971) that high yield on plots with two 1 Department of Agric. & Environmental Resources Engineering, University of Maiduguri, Maiduguri. Nigeria http://www.azojete.com.ng/ AZOJETE Vol. 5 2007 55 cultivations was due to effective weed control. Stach (1992) conducted a study on soil cultivation in relationship to the development of weeds and reported that weeds occurred at higher frequencies on no-tilled plots. In a study on the effect of reduced tillage systems on weed population in Denmark, Thorup (1985) reported that, in general, reduced tillage cost less, gave higher yields and significantly reduced the stand of weeds. Even though there are many reported literature (some as cited above) on the effects of tillage practice on weed control, there are only very few information on this for the semi-arid environment of North-Eastern Nigeria. Therefore, the objective of this study was to compare the effects of four tillage treatments on weed control in a maize field on a sandy loam soil and to establish the most suitable weed control tillage method in semi arid environment like North-east Nigeria. 2. Materials and methods 2.1 Experimental area The experiment was carried out under rain-fed conditions at the University of Maiduguri Teaching and Research farm in 1999 and 2000 farming seasons. The soil has a sandy loam texture (77% sand, 6% silt and 17% clay) (Rayar, 1984). Rainy period in the study area is usually between June and September, a period of about four months. The total rainfall in the area was recorded as 822.6mm in 1999 and 650 .4 mm in 2000 (Daura, 2001). Some of the common weeds available in the study area are: striga generoides, striga hermontheca, striga aspera, Gamba grass macuna and some volunteer plants. 2.2 Experimental treatments and field layout A 16-plot experiment consisting of four tillage treatments with four replications was set up in a randomised complete block design. The treatments were: zero tillage (T1), disc ploughing (T2), disc harrowing (T3), and disc ploughing followed by disc harrowing (T4). The plot size was 18 m x 5 m with alleys of 4 m between replications and 8 m between the plots. This was to accommodate the width and length of the tractor with the implement and to allow the tractor gain speed before the tillage operation was carried out. Disc ploughing was done at an average depth of 20 cm with a 3 – furrow mounted plough, and harrowing with an offset disc harrow at an average depth of 15 cm. Zero tillage involved planting on bare land with minimum soil disturbance. Treatment T4 involved ploughing followed by harrowing. 2.3 Determination of plant and weed parameters Maize variety, Suwan-1-SR was planted on 8th July 1999 and 28th June 2000. Planting was done manually by placing 3 seeds/hole at an interval of 0.30 m along the rows and 0.90 m between the rows at an average depth of 5 cm. Thinning to 1 stand/hole was done at 3 weeks after planting (WAP). Fertilizer, in the form of NPK (15:15:15), was applied at the rate of 400 kg/ha at 2 WAP followed by a second dose of urea at 200 kg/ha at 6 WAP as recommended by Anonymous (1989). First weeding was done manually using a hoe at 3 WAP. Second weeding using the same tool was carried out at 7 WAP. The last weeding was done to facilitate harvesting at 12 WAP. For both years, the crop was harvested at 13 WAP. The parameters studied during the growth period were plant height (cm), weed density (No/m2), fresh weed weight i.e. weed biomass (g/m2) and the grain yields (kg/ha). Two weeks Effects of Tillage Treatments on Weed Control in a Maize Field on Sandy Loam Soil of North Eastern Nigeria 56 after emergence, five plants from each plot were selected at random and their heights measured using a meter rule. The measurement was done from the ground surface to the tip of the last leaf. Average of these was taken and recorded. At each weeding period, the weed density was determined according to the method described by FAO (1994), while the method described by Olofintoye (1989) was used to determine the weed biomass. The yield from each plot was obtained and expressed in kg/ha. Average values of the plots for each treatment were recorded as the yield of that treatment. Analysis of variance was used to study the statistical differences between the treatments for each parameter at 5% level of significance. Where there was statistical difference, Duncan Multiple Range Test was used to compare the different treatment means. 3. Results and discussion 3.1 Plant parameters Plant heights were measured from 2 WAP at two weeks intervals up to 12 WAP and the values are shown in Tables 1 and 2 for 1999 and 2000 respectively. In the first 2 measurements, the rate of growth was low in all the treatments for both years. As from 6 WAP, plants in the tilled treatments were observed to be taller than those in zero-tillage treatments. Treatment T4 was the best within the tilled treatments in terms of plant height. It was observed that there were significant differences in the plant height as from 4 WAP up to harvest. The significance in the plant height could be due to tillage treatments. Ojeniyi(1986) also reported that different tillage treatments caused significant differences in the height of maize plants. Table 1: Effects of tillage treatments on plant height, cm (1999) Treatment Weeks After Planting (WAP) 2 4 6 8 10 12 T1 12.09*NS 29.50 a 58.09 6 137.36 a 156.55 c 159.97 a T2 13.56 NS 35.646 82.94 a 159.46ab 180.41 a 184.876c T3 12.68NS 35.426 64.696 141.20ab 168.86abc 172.79abc T4 13.19NS 37.99b 90.98a 165.38b 179.92ab 186.45c SE 0.80 2.14 6.74 10.34 7.52 6.21 * = Mean values of four replicates NS = Not significant a,b,c = Means in the same column followed by the same letter are not significantly different at P<0.05(DMRT). AZOJETE Vol. 5 2007 57 Table 2: Effects of tillage treatments on Plant height, cm (2000) Treatment (WAP) 2 4 6 8 10 12 T1 12.95*NS 27.41b 61.94c 141.62bc 163.41c 169.28c T2 13.71 NS 31.15ab 85.32ab 163.15ab 191.32ab 215.13ab T3 13.12NS 32.54ab 83.16ab 158.76abc 178.15abc 192.81b T4 14.23NS 34.73a 91.75a 169.81a 205.36a 221.57a SE 0.91 2.36 7.42 9.85 9.04 5.46 * = Mean values of four replicates NS = Not significant a,b,c = Means in the same column followed by the same letter are not significantly different at P<0.05(DMRT). 3.2 Grain yield The grains were weighed after threshing and average values obtained were converted to kilogramme per hectare as recorded in Table 3. The highest yield of 854.26 and 972.73 kg/ha were obtained in treatment T4 and the least of 638.78 and 714.25 kg/ha in treatment T1 for 1999 and 2000 respectively. Water logging was observed in some plots during the growth period. Also, termites attacked the plots, which led to falling down of some stalks. This happened when there was a short period of dry spell during the growth period. Statistical analysis showed that grain yield was significantly affected by tillage treatments. Tillage significantly increased grain yield in both years. Table 3: Effects of Tillage treatments on grain yield, Kg/ha Treatment (Year) 1999 2000 T1 638.74*a 714.25c T2 767.04bc 872.37ab T3 750.10abc 815.01bc T4 854.26c 972.73a SE 53.35 56.12 * = Mean values of four replicates a,b,c = Means in the same column followed by the same letter are not significantly different at P<0.05(DMRT). 3.3 Weed parameters Table 4 shows the values of weed density in the studied tillage treatments for 1999 and 2000 farming seasons. The values indicated that treatment T1 had the highest number of weed per square meter throughout the period of study for both years. It was observed that the highest value of weed density (171.25 and 197.12 No/m2) occurred in treatment T1 and the least of (72.25 and 81.18 No/m2) in 1999 and 2000 respectively in treatment T4 before the first weeding was conducted. Even at harvest, the highest weed density was observed in treatment T1 and least in T4 for both years. This could be the reason why plants in treatment T1 were shorter than those in the tilled treatments as seen in Tables 1 and 2. The weed densities were Effects of Tillage Treatments on Weed Control in a Maize Field on Sandy Loam Soil of North Eastern Nigeria 58 lower in the tilled treatments when compared to treatment T1. This may be the reason for higher grain yields in the tilled treatments. Since for higher yield, the crop should be more competitive and thus tend to suppress the weed population. Statistical analysis shows that tillage treatments had significant difference on weed density. This result agrees with the report of Campbell et al. (1998) which said that differences in weed density with tillage treatments were significant. Table 4: Effects of tillage treatments on weed density, No/m2 Treatments 1999 2000 WAP WAP 3 7 12 3 7 12 T1 171.25*a 103.13a 47.83a 197.12a 120.46a 61.34a T2 76.756 39.88b 23.42b 121.35b 77.38a 51.13a T3 79.75b 49.88b 27.75b 137.57b 82.14a 54.15a T4 72.25b 36.38b 20.42b 81.18c 31.75b 29.24b SE 11.62 17.82 5.50 15.13 20.25 7.24 * = Mean values of four replicates a,b,c = Means in the same column followed by the same letter are not significantly different at P<0.05(DMRT). The mean weed biomass is shown in Table 5 for both 1999 and 2000 farming seasons. At first measurement, the highest value of weed biomass was recorded in treatment T1 (707.22 and 825.12 g/m2) and least of 155.68 and 215.81 g/m2 for 1999 and 2000 respectively in treatment T4 .This could be attributed to the ploughing and harrowing operations that buried the weed seeds in the tilled treatments. These operations finally resulted to lower weed density and consequently the weed biomass in those treatments. At harvest, the highest weed biomass was observed in treatment T1 for both years. This observation was similar to that of Mimorovic et al. (1998) where no-tillage gave the highest weed biomass at harvest. Statistical analysis showed that weed biomass was significantly affected by different tillage treatments throughout the study period. Table 5: Effects of tillage treatments on weed biomass, g/m2 Treatments 1999 2000 WAP WAP 3 7 12 3 7 12 T1 707.22*a 309.98a 34.05a 825.12a 481.39a 54.75a T2 159.15b 243.74b 16.18b 268.31b 302.05b 40.32ab T3 183.30b 282.79b 18.74b 294.17b 357.21b 43.67ab T4 155.68b 197.87b 15.84b 215.81b 276.17b 36.32b SE 46.95 31.41 4.06 51.26 43.14 9.31 * = Mean values of four replicates a,b,c = Means in the same column followed by the same letter are not significantly different at P<0.05(DMRT). AZOJETE Vol. 5 2007 59 4. Conclusion The results obtained from this study showed that there were significant differences between tillage treatments and all the measured parameters. It was found that treatment T4 performed the best in terms of grain yield and weed control, while treatment T1 performed the least. Grain yield in treatment T4 was 34 and 36% higher than in treatment T1 for the year 1999 and 2000 respectively. When comparing treatments T1 and T4 on the basis of weed control at harvest, there was a decrease of about 57 and 52% of weed density in 1999 and 2000 respectively. Weed biomass also decreased by 53 and 34% in 1999 and 2000 respectively. Based on these findings, it is recommended that disc ploughing followed by disc harrowing should be adopted by farmers for better weed control in maize field in the North-Eastern region on a sandy loam soil. However, the ploughing can be done at a shallow depth so as to avoid waterlogging problems since the soils are light soils. References Anonymons (1987). 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