Low productivity is a feature of Ethiopian agriculture, which can be ascribed to soil deterioration and inadequate water utilization. In view of this, a field experiment was conducted over four years in a permanent plot to assess the effects of cropping systems and tillage methods on growth, yield, and yield components of Maize and to determine optimum management options for better yield production and land use management. The experiment was factorial with two factors: two tillage systems (conservational tillage with crop residue cover and conventional tillage), and two cropping systems (sole and intercropping). The treatments were arranged in a randomized complete block design (RCBD) with three replications. The pooled mean analysis of variance revealed that higher yield and yield components of maize were achieved from conservation tillage over conventional tillage. Under conventional tillage and conservation tillage, the intercropped treatment yielded a 27.70% to 28.30% relative yield advantage over solitary cropping, indicating that productivity of maize and haricot bean intercropping was superior in resource use efficiency than sole cropping. According to the findings, conservation tillage combined with maize-haricot bean intercropping should be recommended to produce better and sustainable maize yields in semi-arid locations.
Conservation tillage; Cropping systems; Crop residue; Intercropping; Relative yield
Low productivity is a feature of Ethiopian agriculture, which can be ascribed to soil deterioration and inadequate water utilization. Even in years of abundant rainfall, the country's soil and water resource usage inefficiency are so severe that it is unable to produce enough grain to feed its population [1]. Despite the existence of potentially productive resources for food self-sufficiency and even surplus production, domestic grain production is expected to satisfy only about 70% of the total food requirement, and 4 to 6 million people require food aid each year [2]. Almost all of the country's crop cultivation is done by smallholder farmers who use traditional ploughing methods.
Conventional tillage (CT) is a frequently used tillage method, which primarily improves the soil’s physical properties [3]. However, CT has the potential to reduce soil organic matter due to enhanced decomposition rate and hence, negatively affect long-term crop productivity, nutrient uptake, and soil health [4]. The previous study also confirmed that organic matter mineralization is enhanced through conventional tillage [5, 6].Under conventional tillage soil organic matter is lost easily [7]. Inversion of the topsoil speeds up the breakdown of organic matter (oxidation) resulting in nutrient losses [8]. Soil erosion depletes soil productivity resulting in adverse physical, chemical and biological soil properties affecting crop yields [9]. In an experiment carried out in Kenya, soil erosion was found to cause a loss of 42 t/ha of topsoil with a run-off of 98,750, litres/ha in 12 months [10].
Tillage systems being developed and studied to address these concerns can broadly be termed conservation tillage. Conservation agricultural activities, which were first pushed by the FAO, were one of the measures launched in Ethiopian agricultural systems to reduce soil and water resource degradation. Conservation agriculture, according to FAO (2001), attempts to make better use of agricultural resources by integrating the management of available soil, water, and biological resources with fewer external inputs. Conservation tillage is defined by three principles that are mutually reinforcing: 1) continuous no- or minimal mechanical soil disturbance (i.e., direct sowing or broadcasting of crop seeds, and direct placement of planting material in the soil); 2) permanent organic-matter soil cover, especially by crop residues and cover crops; 3) diversified crop rotations in the case of annual crops or plant associations in case of perennial crops, including legumes. Conservation tillage with crop residue cover reduces soil manipulation, saves on labour requirement, improves soil productivity by minimizing compaction and improves soil moisture storage within the plough layer thus reducing soil and water losses [11].
Conservation tillage with cover crops protects the soil from splashing rains where they reduce raindrop impact leading to reduced surface run-offs. They improve soil’s physical, chemical, and biological properties (Triomphe and Sain, 2004).Cover crops break soil hardpans resulting in high infiltration of rain and irrigation water [12]. They reduce weeds and increase soil organic matter content thus improving soil fertility [13]. Crop residue mulches protect surface soil aggregates from breakdown and dispersal. Consequently, surface sealing or crusting, water runoff, and soil erosion are reduced [14].
Agriculture production in Ethiopia is low and declining, and natural resource degradation is widespread. Soil erosion costs the country 30,000 hectares of land, or one billion tons of topsoil, 30 kilos of nitrogen, and 15-20 kilograms of phosphorous each hectare [15]. Crop yields have decreased as a result of severe soil degradation, and the effectiveness of fertilizer application in increasing farm production has decreased [16]. Continued soil deterioration is jeopardizing global food security and the livelihoods of millions of rural families. The main causes are not only intensive soil preparation by hoeing or plowing, but also deforestation, crop residue removal or burning, poor rangeland management, and insufficient crop rotations that do not maintain vegetative cover or allow for adequate restitution of organic matter and plant nutrients. The soil is exposed to climatic dangers such as wind, rain, and sun as a result of these operations. In certain climate zones, the extensive and ongoing use of the plow has thus been shown to be unsustainable (Govaerts, 2009). There is an ever-increasing concern that it is becoming more and more difficult to achieve and sustain agricultural productivity and food security through conventional tillage and extensive farming system since there is land degradation, soil erosion, and limited opportunities for area expansion.
Shalla is among maize and haricot been producing Woreda under conventional tillage system. Although most of the mid and low-altitude areas of the woreda are suitable for maize and haricot bean production, the productivity of maize-haricot bean intercropping under conservational tillage and conventional tillage are limited mainly due to a lack of information on suitable and appropriate cropping systems and tillage systems. There was no research conducted in the area on cropping systems (sole and intercropping) and tillage systems (conservational tillage and conventional tillage). It has been very difficult to address the increasing demand for food security by producing adequate grain yield in quality and quantity due to high soil erosion by rain and winds. In view of this, the present investigation was conducted to(1) evaluate the growth and yield performance of maize in the sole and intercropping under conservation tillage and conventional tillage, (2) determine economic benefits and land-use efficiency of maize-haricot bean intercropped under conservation tillage and conventional tillage.
Description of the Study Area
The field experiment was conducted for four consecutive cropping seasons (2014-2017) in a permanent plot at Shallaworeda, Awara Gama Kebele of West Arsi zone, Oromiya Region. The experimental site is located at 7016’55’’ N latitude and 38027’27.8” East longitude with at an altitude of 1696 meters above sea level is found 282 km south of Addis Ababa. The long-term average annual rainfall of 750 mm with a mean temperature of 18.50C. The major crops grown around the experimental area include maize, haricot bean, teff, finger millet, sorghum and potatoes. Maize is the most dominant food crop grown by farmers in the area. Maize and haricot bean are grown mainly as cash crops.
Treatments and Design
The experiment was factorial with two factors: two tillage systems (conservational tillage with crop residue cover and conventional tillage), and two cropping systems (sole and intercropping). The treatments were arranged in a randomized complete block design (RCBD) with three replications. The land was prepared to be designed for both conventional tillage and conservation tillage, and then it was planted following the field layout.The experimental treatment combination, sole maize under conservation tillage with crop residue cover, sole haricot bean under conservation tillage with crop residue cover, sole maize under convention tillage, sole haricot bean under conventional tillage, maize-haricot bean intercropped under conservation tillage with crop residue cover and maize-haricot bean intercrop under convention tillage were evaluated as in 7.5m length x 6.40m width = 48m2 for each plot.
The paths between blocks and plots were 2.5m and 2m, respectively. Each block contained all four treatments randomly assigned to each plot. The spacing for sole and inter cropped maize was 80 cm inter–row spacing and 25cm intra-row spacing accommodating eight maize rows, each row of maize consisted of 30 plants. The inter-cropped haricot bean was planted as pair of rows having 40 cm space between them,10cm between plants and 20 cm far from each maize row. Only the central six rows of maize were subjected for data collection. Grain yield was taken from the central four rows of maize and ten rows of haricot bean by excluding first rows for border effects in each side of the plots.
In conventional cultivation, the land was prepared by oxen ploughing three times before planting. In conservation tillage furrow was opened using a narrow slot (5-10cm wide) in the soil for seed placement without mechanical or secondary tillage operation and crop residue covered the surface area as a mulching at the rate of 4 tha-1 to reduce erosion and to control weeds. In maize and haricot bean where conservation tillage was used, weeds were controlled by using Round up 4Lha-1 applied 15 days before planting. The maize and haricot bean were planted on May 18 and June 19, 2016 respectively, in rows and two seeds per hill were planted to assure germination and good stand after which the seedlings were thinned to a single plant per hill. All plots received a 100 kg ha-1 basal treatment of Di-ammonium Phosphate (DAP) (18 percent N, 46 percent P2O5) at the time of planting. Nitrogen was applied to all plots in the form of Urea (46 percent N) at a rate of 100 kg ha-1 in a split application, with the first half treated at the knee-height stage of maize and the second half applied immediately before tasseling.
Parameters for maize component
Plant height was measured in (cm) as the height from ground level to the base of the tassel by taking ten randomly selected plants per plot using measuring stick. Ear heightwas measured (in cm) as the height from ground levels to the base of the lower most ears from ten randomly taken plants per plot using measuring stick. Leaf area at 50% silking was taken by measuring the leaf length and maximum leaf width and was adjusted by a correction factor (0.75 i.e. 0.75 x leaf length x maximum leaf width). Leaf area index was calculated as the ratio of total leaf area per ground area occupied by the plant [17]. The ground area was calculated for both sole and intercrop as 80 cm x 25 cm=2000 cm2.
Cob length was measured (in cm) from base level to the tip along the length of the cob from ten randomly selected cobs per plot with ruler and the average were recorded.Above ground, biomass was determined after the crop was harvested. The stalk from the net plot was oven dried at 700c until constant weight was achieved, before weighing and converting it to per ha basis. Number of kernels per cob was counted as product of number of rows per ear and number of kernels per row of randomly selected ten cobs per plot during harvesting. Grain yield per ha was obtained from the central four rows of maize, and then the yield was measured after the seeds are picked and shelled by hand. The grain yield was adjusted to 12.5% moisture level and then converted to tha-1.Seeds were counted using an electronic seed counter from a bulk of threshed seed and weighed using a sensitive balance from a plot during harvest, adjusting to 12.5% moisture content. The harvest index was derived by multiplying the ratio of grain yield to above-ground biomass by 100.
Inter cropping efficiency
In evaluating inter cropping efficiency; several procedures are developed by various Workers [18]. An assessment of land return is made from the yield of pure stands and from each separate crop within the mixture. The calculated figure is called the Land Equivalent Ratio, where intercrop yields are divided by the pure stand yields for each crop in the intercropping system and the two figures added together [19] and [20].
Where:
LERCA = Land equivalent ratio under conservation tillage condition
LERCT = land equivalent ratio under conventional tillage condition.
For each crop a ratio is calculated to determine the partial LER for that crop, and then the partial LERs are summed to give the total LER for the intercrop [21].
Data Analysis
The data collected on different parameters was statistically analyzed according to [22] by using SAS statistical software (SAS, 2000) with a general linear model procedure. After performing Analysis of Variance (ANOVA) the differences were compared using the least significance difference (LSD5%).
The initial soil properties of the experimental area
The analytical results of particle Soil samples taken at different soil depths from 0-20 cm, 20-40cm and 40-60 cm showed that, the textural class of the experimental soil was sand clay loam (Table 1). Percentage of clay soil varied from 28.33 to 31.50 % for soil depth of 20-40cm and 0-20 cm, respectively. The soil organic carbon and organic matter content of the top soil (0 to20 cm) was 1.74% and 3.00%, respectively, which is in the medium range, according to [23] the soil organic matter content ranges 1-2, 2-4, and 4-6% are rated as low, medium and high, respectively. The result of soil analysis from 0-20 cm depth also shows that total Nitrogen of 0.34%, available phosphorus about 7.40 parts per million (ppm) and pH of 6.54. Usually, maize prefer soil pH ranges from 6.0 to 7.0 [24], indicating that soil pH of the experimental area was suitable for maize production. In general, soil particles distribution was decreased uniformly with soil depth increases except for Silt.
Soil properties |
Soil depth |
||
0-20 cm |
20-40cm |
40-60cm |
|
Particle distribution |
|
|
|
Sandy (%) |
31.50 |
28.33 |
28.00 |
Clay (%) |
22.50 |
22.33 |
22.00 |
Silty (%) |
46.00 |
49.34 |
50.00 |
Chemical properties |
|
|
|
pH |
6.54 |
6.70 |
7.29 |
Available phosphorus mg kg-1 |
7.40 |
6.77 |
4.31 |
Organic Carbon (%) |
1.74 |
1.71 |
1.60 |
Organic matter (%) |
3.00 |
2.95 |
2.76 |
Total nitrogen (%) |
0.34 |
0.29 |
0.19 |
Table 1: Particle size distribution and selected chemical properties of the soil of the study area prior treatment application
Phenological parameters of maize
Days to 50 percent anthesis, 50 percent silking, and 95 percent physiological maturities did not affect by tillage and cropping systems except 95% of physiological maturities was affected by tillage systems (Table 2). Days to anthesis ranging from 65.11 days for intercropped maize to 65.89 days for sole maize, days to 50% silking ranging from 67.62 days for intercropped maize to 68.93 days for sole maize, while days to maturity ranging from 118.00 days for intercropped maize to 118.60 days for sole maize. Days to 50 percent anthesis ranged from 64.99 days for maize grown under conventional tillage to 66.02 days for maize grown under conservation tillage. Days to 50% silking ranged from 67.60 days for conventional tillage to 68.95 for maize grown under conservation tillage. Days to 95 percent physiological maturity ranged from 116.10 days for maize grown under conventional tillage to 120.50 days for maize in conservation tillage. However, days to anthesis, silking and physiological maturity in this study did not show significant effect by the interaction between cropping system and tillage system. This might be because of more efficient use of soil moisture by intercropped as described by Morris and Garrity (1993), claiming that water use efficiency by intercrops greatly exceeds the sole crops, often by more than 18% and even by as much as 99%.
Treatments |
Days to50% anthesis |
Days to50% silking |
Days to 95% Phenological maturity |
Cropping system |
|
|
|
Sole |
65.89 |
68.93 |
118.0 |
Inter cropping |
65.11 |
67.62 |
118.6 |
LSD |
1.70ns |
1.75ns |
1.74ns |
Tillage system |
|
|
|
CA |
66.02 |
68.95 |
120.50a |
CT |
64.99 |
67.60 |
116.10b |
LSD |
1.70 ns |
1.75 ns |
1.74 |
CV (%) |
1.84 |
1.81 |
1.04 |
Table 2: Phenological parameters of Maize grown in sole and intercropping under conservational tillage and conventional tillage in 2017.
Means in the same column followed by the same letters are not significantly different (p < 0.005).
Growth parameters of maize
Plant height, ear height, cob length, leaf area and leaf area index were not significantly affected due to varied cropping systems (Table 3). Although non-significant effects revealed in all growth parameters, the maximum values were observed in sole cropping system over that of intercropped. However, tillage practices had significant effects on plant height, ear height and cob length. Despite non-significant effects of tillage practices on leaf area and leaf area index observed, conservation tillage tended to give positive influences in all parameters, compared to conventional tillage.These findings could be explained by the residue's surface placement, which lowered N mobilization at the beginning when compared to straw integrated into the soil. Because of higher changes in surface temperature and moisture, as well as reduced nutritional availability to bacteria, [25] reported similar results [26, 27]. Soil-incorporated residues tend to decompose faster than surface residues and have a higher potential for N immobilization [28]. The fast growth rate obtained at the middle age of crop in conservation tillage than conventional tillage might have been due to N fertilizer applied at middle age of maize in the form of Urea. The nitrogen fertilizer might have accelerated the decomposition rate of mulch, which helped the plant to get additional nutrient and resulted in increased growth rate. Similar results were reported by [29] where residue added to soil with manure or nitrogen fertilizer led to residue decomposition rates that were two times greater than when no amendments were added.
Treatments |
PH |
EH |
CL |
LA (m2) |
LAI |
cm |
|||||
Cropping system |
|
|
|
|
|
Sole |
213.50 |
108.17 |
19.13 |
5274 |
2.64 |
Inter cropping |
208.50 |
105.67 |
17.85 |
4515 |
2.26 |
LSD |
24.92ns |
11.25ns |
1.48ns |
1419ns |
0.71ns |
Tillage system |
|
|
|
|
|
CA |
230.30a |
116.33a |
20.81a |
5437 |
2.72 |
CT |
191.70b |
97.50b |
16.18b |
4352 |
2.18 |
LSD |
24.92 |
11.25 |
1.48 |
1419.3ns |
0.71ns |
CV (%) |
8.36 |
6.75 |
2.62 |
20.53 |
20.53 |
Table 3: Growth parameters of maize grown in sole and inter cropping under conservation tillage and conventional tillage
Means in the same column followed by the same letters are not significantly different (p<0.05), CA- conservational tillage, CT- conventional tillage.
Yield, yield components and harvest index
Pooled mean analysis of variance revealed that cropping systems were significantly (P < 0.05) affected 100-seed weight, grain yield ha-1, and total biomass. Sole cropping system outperformed over intercropping, possibly due to lessresources competition for growth in sole system than intercropping, particularly for soil moisture. The mean seed number cob-1, seeds per plant, 100-seed weight, grain yield ha-1, and total biomass rangedfrom 498g, 194.20g, 38.63g, 3.58 t ha-1, and 11.48tha-1for inter cropped maize to 510.20g, 216.60, 41.52g, 3.93 t/ha, and 13.45 tha-1for solemaize, respectively (Table 4).The number of seeds per cob did not differ significantly (P < 0.05) depending on the cropping system. However, cropping system had a substantial (P < 0.05) impact on harvest index. The maximum harvest index was achieved from the intercropped treatment. This was possibly due to better availability of soil moisture, since intercropping can improve canopy cover and thus protect soil surface evaporation [30].
Like cropping systems, tillage methods had significant effects on seed number per cob, 100-kernel weight, grain yield, total biomass, and harvest index (Table 4). The higher values of seed number per cob, 100-kernel weight, grain yield, total biomass was achieved in conservation tillage system. Seed number per cob, seed plant-1, 100-kernel weight, grain yield ha-1, and total biomass, decreased under conservation tillage were increased by 6.41, 10.95, 11.70, 9.62, and 15.6%, respectively when compared to conventional tillage. These results are in line with [31]. Similarly, [32] and [33] reported better soil moisture contents under conservation tillage compared to conventional tillage, this phenomenon increased water infiltration rates and reduced evaporation from the soil surface. According to other authors, yields with no-till are usually comparable to those from conventional methods in years with a consistent rainfall pattern, with higher yields in dry years and lower yields in rainy years [34-37]. However, greater harvest index was recorded in conventional tillage, compared to conservation tillage. Correspondingly, Ahadiyat and Ranamiukhaarac-hchi (2008) reported that conventionally tilled plots gave a higher harvest index.
Treatments |
NSPC |
100-seed weight (g) |
Grain yield (t/ha) |
Total biomass (t/ha) |
Harvest index (%) |
Cropping system |
|
|
|
|
|
Sole |
510.20 |
41.52a |
3.93a |
13.45a |
29.67b |
Inter cropping |
498.00 |
38.63b |
3.58b |
11.48b |
31.18a |
LSD |
14.81 |
2.57 |
0.31 |
1.93 |
2.92 |
Tillage system |
|
|
|
|
|
CA |
520.80a |
42.56a |
3.95a |
13.48a |
29.67b |
CT |
487.40b |
37.58b |
3.57b |
11.45b |
31.46a |
LSD |
14.81 |
2.57 |
0.31 |
1.93 |
2.92 |
CV (%) |
2.10 |
4.54 |
5.88 |
10.94 |
6.80 |
Table 4:Yield and yield component of maize grown in sole and intercropping under conservational tillage versus conventional tillage.
Means in the same column followed by the same letters are not significantly different (p < 0.05), CA-Conservational tillage, CT-conventional tillage.
Efficiency of intercropping of maize and haricot bean grown under conservation tillage and conventional tillage
The partial land equivalent ratio (PLER) of maize and haricot bean, as well as the total land equivalent ratio (TLER), did not change significantly between conservation and conventional tillage (TLER) (Table 5). Slightly higher (0.92) PLER was obtained maize grown under conventional tillage comparing to maize grown under conservation tillage (0.89). Slightly higher partial LER of haricot bean (0.39) was obtained when haricot bean was intercropped with maize under conservation tillage. The lowest partial LER (0.36) was obtained when haricot bean was inter cropped with maize under conventional tillage. The partial LER of component crops i.e., maize and haricot bean were calculated as 0.89 and 0.39 respectively for maize grown under conservation tillage, with a total LER of 1.283. The partial LER of maize and haricot been grown under conventional tillage was 0.92 and 0.36, respectively with total LER of 1.277. The total LER for all intercropping treatments were greater than one, indicating that all the treatments had an advantage in land use.
Land equivalent ratio (LER) analysis indicatedthat 27.70% to 28.30% relative yield advantage was obtained by the intercrop over the sole cropping under conventional tillage and conservation tillage respectively. This implies that the productivity of intercropped maize with haricot bean was greater in resource use efficiency as compared to sole cropping in both conservation tillage and conventional tillage.
Treatments |
Yield of maize (t ha-1) |
Yield of haricot bean (t ha-1) |
Partial LER of maize |
Partial LER of haricot bean |
Total LER |
Sole |
3.93a |
2.602a |
- |
- |
- |
Inter cropping |
3.58b |
0.968b |
- |
- |
- |
LSD(0.05) |
0.312 |
0.47 |
- |
- |
- |
Conservation |
3.95a |
1.80 |
0.89 |
0.39 |
1.283 |
Conventional |
3.57b |
1.77 |
0.92 |
0.36 |
1.277 |
LSD(0.05) |
0.312 |
0.18 ns |
0.34 ns |
0.16 ns |
0.37 ns |
CV (%) |
5.88 |
7.09 |
10.65 |
12.18 |
0.31 |
Table 5: Efficiency of inter cropping of maize and haricot bean grown under conservation tillage and conventional tillage
Means in the same column followed by the same letters are not significantly different (p < 0.05) (5%), CA= Conservational tillage, CT=conventional tillage, LER=land equivalent ratio.
In general, high yield was obtained under conservation tillage than conventional one. This may be due to conservation tillage reducing surface crusting and high fluctuation in soil temperature, crop residue protecting soil from excess solar radiation, absorbing the kinetic energy of raindrops, forestalling water evaporation and holding more moisture, reducing runoff and soil erosion,increase soil organic matter content thus improving soil fertility, suppress weed growthand reducing the population of weeds, which compete with crops for water, nutrients and sun light. This suggests the potentials for buildup of cumulative effects to result in significant on crop growth, yield and yield components under conservation tillage. Land equivalent ratio (LER) analysis indicatedthat 27.70% to 28.30% relative yield advantage was obtained from the intercropped treatment over the sole cropping under conventional tillage and conservation tillage, respectively indicated that productivity of intercropping maize and haricot bean was greater in resource use efficiency as compared to sole cropping. From the results, it can be concluded that conservation tillage with maize-haricot bean intercropping give high maize yields in semi-arid areas. It is therefore, recommended to use this combination in order to get high maize yields in semi-aridareas.
Citation: Nigussei A, Daba D (2022) The Influence of Cropping systems and Tillage practices on Growth, Yield, and Yield Components of Maize (Zea may L.) in Shalla District, West Arsi Ethiopia. J Agron Agri Sci 5: 031.
Copyright: © 2022 Ashenafi Nigussei, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.