This experiment compared performance of maize crops as planted by two types of seeders (Precision Seeder and BARI Seeder) and manually (hand planting). Details on about the machines, experimental procedure and performance data collection and processing are summarized below.
The Seeders:
The Precision Seeder (PS) and BARI Seeder (BS) used in the experiment are shown, respectively. Key specifications of the machines are presented. In the 2019 model of the PS, the furrow openers were set on a separate frame behind the rotavator (in 2018 model, they were set on the rotavator mudguard that used to bend rearward under load during field operation) to avoid bending as suggested in the previous year’s report. Further, the press wheels were made little bit narrower (38 mm) than the 2018 model (41 mm) to allow easy penetration into the tilled furrows strips and assure optimum furrow compaction. It can be noted that the PS uses Chinese precision seed meters that have high seed simulation efficiency (93–97%), low doubles (<3%) and zero seed locking (Matin et al., 2019; Saha et al., 2018).
Field Preparation and Planting
The strip-till planting experiment was conducted at the research farm of FMPE Division, Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur during the rabi season of 2019–’20. The soil was clay-loam type. The previous puddled aman rice (monsoon rice) was harvested manually on 3 November 2020 leaving about 250 mm long rice stalks (≡2.57±0.60 t ha-1 fresh residues) in the field. The field was then applied with herbicide round up (that killed the weeds) and allowed to dry to reach joe condition before strip-till plating of maize. As it rained intermittently during October–November, the process of soil drying was slow and the soil moisture at planting was 31.2±2.4% (dwb) which was wetter than the desired joe condition on the day of planting (5 December 2019). The experimental plots were 13 m long and 3.6 m wide and had 1.0 m footpaths in between them.
Hybrid maize variety Elite (95% germination capacity) was planted by both the machines and manually (hand planting) with a targeted row spacing of 0.6 m and plant spacing of 0.2 m. Each plot accommodated 6 rows of maize. Elite variety was chosen due to its dented shape (the most challenging shape to meter accurately) which is prone to high seed metering error compared to flinted/round shaped maize seeds. The seeders completed planting operation (opening strip-tilling furrows, placing seeds, covering seeds with loose soil and compacting furrow) in a single pass of the machines. Contrary, the hand planting operation required tilling the plots three times over the previous week, hand levelling that tilled plots, and at the day of planting manual digging of furrows and seed placement in furrows followed soil covering and furrow compaction by treading.
Machine Set up, Operation and Maize Planting
These 1.2 m wide seeders planted two rows of maize in each pass of the machine; thus requiring three passes to cover each plot (6 rows). One person operated the machine and one helper assisted him in setting up, seed filling, etc. Before start of planting in the experimental plots, each machine was calibrated for seeding depth (targeted for 50 mm) and row spacing in the adjacent field. Any residue raked during planting in the experimental plots was cleared by the assistant. During machine planting any seeds left uncovered were not disturbed or put pack into soil. Problems encountered during operation of the seeders were recorded for future reference and their improvement/fine tuning.
Crop Management
FRG 2018 (BARC, 2018) recommended package of fertilizer (cow dung 623 t ha?1, urea 520 kg ha?1, TSP 250 kg ha?1, MoP 175 kg ha?1, Zypsum 250 kg ha?1, ZnSO4 15 kg ha?1, Boric Acid 7.7 kg ha?1) was applied (urea was split into one basal dose and two top dressings). In case of machine planting, the basal fertilizers were broadcasted on each plot immediate before planting whilst the top dressed urea fertilizer was applied along the plant rows at 30 DAP and 50 DAP. In case of the control plots (hand planting) the basal fertilizers were applied before the last tillage pass whilst the top dressed urea dosages were applied along the rows at 30 DAP and 50 DAP. It rained a few times over the crop growing period, so irrigation water was applied as and when necessary. Weed control was done chemically (applied PANIDA at 5 DAP @3 ml l-1 water per decimal of land and Calaris Extra at 25 DAP @6 ml l-1 water per decimal of land). Thinning of extra maize plants was done at 42 DAP.
Data Collection and Processing
Three soil samples were collected from the experimental field on the day of planting using an augur and oven dried at 105 °C for at least 72 hours to determine soil moisture content. Immediate after planting all the plots, number of uncovered maize seeds in each plot was counted and expressed as uncovered seeds plot?1. Furrow depth and furrow width were measured from 10 locations in a randomly selected furrow in each plot on the same day. Furrow backfill (depth of loose soil in the furrow after planting) were also measured from 10 locations in a randomly selected furrow in each plot on the day. All the data were expressed as their averages for each plot.
In order to calculate the emergence rate and days to 50% germination, number of plants germinated each day were recorded from 3 rows (3 m section of each row) from each plot during 5–25 DAP. At 26 DAP, seeding depth was measured as shown by uprooting plants (10 plants per plot) from the sixth row (adjacent to footpath) in each plot. Thus, only five rows of maize plants finally remained in each plot until harvest.
Plant height was measured at 35 DAP and at harvest. The crop was harvested on 19 May 2020 (additional days after maturity were allowed for field drying of maize cobs before harvest). Agronomic data (plant population; cobs per plot; cob length and diameter; grains per cob; 100 grain weight; grain and stover yield per plot, and grain moisture content) were recorded. Yield of grain was adjusted at 15% moisture content. The data were analyzed for means (M) and standard deviations (SD).
Observation Trials
Three strip-till observation trials were set up on 4 December 2019 at an adjacent field (13 x 3.6 m plots) for wheat, chickpea and soybean. No data were collected except photographs.