Effect of tillage practices on moisture retention and maize (Zea mays L.) performance under rainfed conditions in Swaziland
Abstract
An experiment was conducted to determine the effect of tillage practices on moisture retention and maize performance under rainfed co nditions in Swaziland. The five treatments were based on structure of seedbed and seed planting method. They were ; zero tillage where jab planter was used to directly seed (JAB), tractor drawn planter to directly seed without ploughing (TDSS), tractor dra wn cultivator to loosen soil followed by planting with tractor planter (TDRDS), planting basics made by using hand hoe (PLB) and conventional tillage (CNT) which was used as a control. The treatments were replicated three times. The data collected included weather data, germination counts, plant height, moisture retention, total dry matter and dry grain yield. The results displayed a significant difference in terms of moisture retention for the majority of the periods where measurements were done (p<0.05). Conventional tillage retained the least moisture while JAB retained the most moisture. In terms of seed emergence, TDRDS had the highest emergence during the first seven days compared to the other treatments. Conventional tillage had the tallest plants (26 8.5 cm) compared to the other treatments at 21 days after planting. Conventional tillage also had the highest total dry matter (16.2 tons/ha) and planting basins had the lowest dry matter (12.6 tons/ha). TDRDS had the highest grain yield (9.9 tons/ha), and JAB had the lowest grain yield (9.1 tons/ha). The difference in mean total dry matter and mean grain yield was not significant (p>0.05).
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Introduction
Maize ( Zea mays ) is Swaziland’s staple food crop and is produced by over 90% of small holder farmers on communal land [1]. The crop is grown mainly for subsistence purposes. While almost all homesteads in the communal land produce maize, the country has never reached self-sufficient levels in maize produ ction [2]. As a mitigation strategy, the gaps in production are covered by imports from South Africa which is the neighbouring country.
Maize can be grown on a wide variety of soils, but performs best on well-drained, well-aerated, deep warm loams and silt loams containing adequate organic matter and well supplied with nutrients [3]. It can be grown successfully on soils with a pH range of 5.0 - 7.0, but a moderately acid environment of pH range 6.0 - 7.0 is optimum. Values outside this range may result in nutrient deficiency and mineral toxicity. Addition of lime is recommended for good yields on more acid soils.
Availability of moisture in the soil is fundamental for sustainable maize production as maize requires 450 to 600 mm of rainfall per unit areaf or optimum growth [4]. The crop evapotraspiration (ETc) for maize is between 1.09 mm/day and 5.50 mm/day, with average value being 3.33 mm/day [5]. Tillage is practiced to loosen the soil, forming a good medium to enhance uniform seed germination, weed ma nagement and incorporate crop residues [6]. Retaining permanent soil cover in minimum tillage can reduce water requirement for a crop by as much as 30% [7]. Subsoil tillage was reported to decrease water consumption by up to 8% and increase maize yield by up to 674 kg/ha compared to conventional tillage [8]. Tillage may result in high crop yields due to modification of soil’s physical, chemical and biological properties [9]. The objective of the study was to determine the effect of tillage practices on mois ture retention, and maize performance under rainfed conditions in Swaziland.
Conclusion
The study examined the effect of tillage practices on moisture ret ention and maize performance under rainfed conditions. Based on the results it can be concluded that the farming season during which the experiment was undertaken received adequate rainfall, as the total received was within the range of rainwater requireme nt for maize crop. The rains were well spread, and there were no cases of long periods without effective rainfall. CNT conserved the least moisture, as reflected by the higher soil suction values. On the other hand JAB conserved the most moisture. The diff erence in seed emergence was not significant for the different treatments. However, more seed emergence under TDRDS during the first seven days after planting. It was followed by CNT. CNT produced the tallest plants at 21 days after planting, even thought he differences in plant height were not significant. CNT produced the highest dry matter, and PLB produced the least dry matter. PLB also produced the least grain yield. TDRDS produced the highest grain yield, even though the difference in grain yield for the treatments was not significant.
