2.1. Experimental site and climatic condition: The entire three years lengthy experiment is conducted in the field research plot of Bangladesh Agricultural Research Institute (BARI), Gazipur, Bangladesh (23 540 41.47920 ’ N and 90 230 20.26320 ’ E). The soil used in this experiment were collected from AEZ (Agro Ecological Zone)-28, Madhupur Tract, deep red brown soil and mostly laterite in nature. The whole experiment was conducted under the same layout, management practices and preferences. The overall climate is the sub-tropical, semi-arid monsoon with a wide variation in rainfall throughout the year.
2.2. Study crop and variety The study crop was Maize (Zea mays) – BARI Hybrid Maize 6. This variety was used throughout the experiment, unless stated otherwise. The seeds of Maize – BARI Hybrid Maize 6 were sown directly in the respective treatment field, while needed special seeder is used.
2.3. Land preparation and soil samples analysis The experimental field was divided into plots based on the experimental design (Split Block Design). The unit plot size was (5 m 6 m) with 1 m buffer distance between the plots. These plots were prepared as per requirement of the tillage practices in different treatments at least seven days before the sowing. Farmers practice plot preparation was done by power tiller mechanical tillage, followed by flood irrigation, but zero tillage/minimum tillage plots were prepared by special tilling equipment. While preparing conservation plots, the previous crop (rice) residue was kept up to 30 cm length on the field. The basal recommended amount of fertilizers was applied before tillage operations. The soil use in this experiment was collected from the (Agro Ecological Zone) AEZ 28-Madhupur tract. The physicochemical properties of soil were tested in two stages, i) Pre sowing period and ii) Post-harvest period. The depth of soil sample collection was 0–30 cm for the further analysis. The physicochemical properties of initial soil presented. The analysis of soil was accomplished following the standard methods.
2.4. Experimental treatment and design The experimental treatments were based on tillage operations and irrigation practices. Three methods of tillage were used in the experiment. These were-
T1 = Zero tillage or no-tillage (strip tillage), no disturbances of the soil, power tiller operated inclined plate planter is used for seed sowing operation. T2 = Minimum tillage; single tillage and the sowing operation performed at once by power tiller operated inclined plate planter. T3 = Traditional tillage operation (farmers practice), usually three to four times tillage with power tiller followed by hand sowing.
Three types of irrigation practice were I1 = Only one irrigation was applied at 25 days after sowing (DAS). I2 = Two irrigation was applied at 25 and 50 DAS, respectively. I3 = Three irrigation was applied at 25, 50 and 85 DAS, respectively.
2.5. Description of tillage practices
(a) Zero tillage (ZT, T1) practices Power tiller was used for zero tillage operation. In the ZT approach, the power tiller operated BARI developed inclined plate planter is using for seed sowing. In zero tillage practices, the soil was pulverized in the form of the strip (6–7 cm) to put the maize seed and the rest of the field was remain undisturbed. For this purpose, the number of tines of power tiller was changed. Six tins were used in zero tillage; at each travel, sowing was done in two rows, for each row only three tins were used. Sowing line to line distance was maintained 75 cm and plant to plant distance was 25 cm. The distance between the line to line and plant to plant is adjusted through plate planter. In zero tillage practices, power tiller operated inclined plate planter was a new mechanism invention of BARI for maize planting. In this practice, only two labors and one inclined plate planter mounted power tiller was required. Two labors and only one power tiller in six hours operation were required for tillage and sowing of each acre area of land. This practice was time and fuel saving method in comparison to the traditional method.
(b) Minimum tillage
(MT, T2) practices Minimum tillage means minimum soil disturbance. The soil was pulverized at modest and least stage. Soil pulverization and maize sowing were done simultaneously. Minimum tillage operation aiming to keep the prior crop residue and removing the weed exposed on the upper soil of the experimental plots. In minimum tillage operation, power tiller operated inclined plate planter has been handed over the soil once to manipulate the soil and the sowing of maize seeds. In minimum tillage operation, three labors and one power tiller was required for six hours in operation for tilling and sowing of maize seeds. Minimum tillage operation can save a substantial quantity of labors and fuel so; the cost of production can be minimized. It is comparatively time and fuel saving methods to the traditional farmers ‘method.
(c) Traditional tillage practices The traditional tillage practices was the farmer’s tillage practice in Bangladesh. This was an intensive tillage operation. Usually four to five cross manipulation of soil was done in this practice. The exposed weeds were removed. In traditional tillage practices, maximum soil pulverization occurred. This treatment covered maximum soil tillage and sowing were done manually. Traditional tillage practices consumed the highest fossil fuel for maximum soil pulverization and power tiller in operation for more time. In traditional tillage, eight labors were required for sowing and soil tillage. One power tiller was required for fifteen hours in operation for tilling one acre of land. The more tilling operation creates an adverse environment for the growth of beneficial soil microorganisms.