Published on International Journal of Agriculture & Agribusiness
Publication Date: March 25, 2019
Kugedera, A. T. & Kokerai, L. K
Great Zimbabwe University, Department of Livestock, Wildlife and Fisheries, Gary Magadzire School of Agriculture and Natural Sciences
Zimbabwe Open University, Department of Agriculture Management, Faculty of Agriculture
Journal Full Text PDF: Effects of In Situ Rainwater Harvesting and Cattle Manure to Improve Sorghum Yield.
The experiment was to determine the effect of using tied ridges and planting pits to improve sorghum yield in the semi-arid areas. The experiment was done as a completely randomised design with six treatments replicated three times. The treatments were; planting sorghum on tied ridges (TR), planting on planting pits (PP), and planting on conventional tillage (CT), planting sorghum in combination of cattle manure with tied ridges (TCM), planting pits (PCM) and conventional tillage (CCM). Sorghum planted under conventional tillage was used as the control. Macia variety of sorghum was planted and the following parameters were measured; grain yield, stover yield and grain moisture content at harvesting. Data was analysed using IBM SPSS version 25. Grain and stover yield were higher from planting pits in combination with cattle manure at 4.4tha-1 and 8.35tha-1 respectively than all other treatments. The yield were significantly different from that under conventional tillage (p<0.05). Grain yields for TR, TC, CT and CM were 1.82 t/ha, 4.30 tha-1, 1.80 tha-1 and 3.81 tha-1 respectively. Grain moisture content for all treatments were less than 16% and not significantly different (p>0.05). Combination of water harvesting and cattle manure improved sorghums yields at large.
Keywords: Tied ridges, planting pits, sorghum, & cattle manure.
Sorghum (Sorghum bicolor L. Moench) is one of the drought tolerant crops grown in arid and semi-arid areas and is the fifth important cereal crop in the world surpassed by maize, wheat, rice and barley (Akram et al., 2007). Sorghum is one of the main staple foods for the world’s poorest and food insecure countries (Timu et al., 2012) such as Zimbabwe, Kenya, Ethiopia and Somalia. Early maturing sorghum varieties such as Vumba, Shirikure and Macia were introduced to improve food security in marginal areas of Zimbabwe and also to improve income after selling surpluses. These varieties are high yielding and thrive well in harsh conditions. The Sorghum is high in starch and low in protein which offers it suitable to be used as staple food (Esipisu, 2011) and alternative source of starch by replacing maize. Sorghum is a drought tolerant crop that can be adopted by farmers in adverse climate areas (Mwangi et al., 2010). Sorghum can survive in areas where rainfall fluctuates and is below 500 mm per year (Muriu et al., 2005; FAO, 2006; Rukuni et al., 2006).
Tied ridging is a semi-permanent ridge with annual ties which are usually 0.5 to 0.65 times the height of the ridge (Munodawafa and Zhou, 2008; Nyakudya and Stroosnijder, 2013) and ties are constructed across furrows annually at a height of about 1m.These ties are constructed to reduce surface runoff (Motsi et al., 2004) and also reduce soil erosion. According to Ndlangamandla et al. (2016) tied ridging is a soil moisture conservation structure that involves the construction of small rectangular basins formed within the furrow of cultivated fields, to increase infiltration and water storage (Wiyo et al., 1999). The stored water can be used by plants for longer period of time compared to when is under runoff (Gichangi et al., 2012) and improved soil moisture retention (Gichangi et al., 2007; Belenchew and Abera, 2010; Kathuli and Itabari, 2013). The use of tied-ridging together with soil fertility improvement increase crop yields by 100-300% (Kathulani and Itabari, 2013). Tied ridges have been found to be the most productive of the rainwater harvesting technologies in semi-arid areas (Motsi et al., 2003; Mutekwa, Kusangaya and Chikanda, 2006). Tied ridges need to be used in combination with other methods such as contour ridges and infiltration pits (Nyamadzawo et al., 2013). Tied ridges in sandy soils did not increase water content in the root zone due to poor water holding capacity of the soil.
Planting pits are shallow holes (< 25 cm deep) which are dug for concentration of surface runoff (Rockström, 2000). According to Kathuli and Itabari (2013) planting pits involves the digging of small holes with a diameter of 30 cm and 15-20 cm deep. Manure or compost is place inside the pit at the bottom and mixed with soil prior to planting (Gichangi et al., 2007; Kathuli and Itabari, 2013). Zai pits are commonly used in West African countries such as Burkina Faso. In semi-arid areas of Zimbabwe such as Chivi, planting pits were promoted by Non-Governmental Organisations (NGO) such as Zvishavane Water Project (ZWP) and CARE. Zai pitting technique in Burkina Faso has been seen to improve millet yield (Rockström, 2000). Pitting technique is also used to conserve soil moisture on steep slopes in Tanzania and they are referred to as matengo pitting (Rockström, 2000). According to Mupangwa et al. (2006) and Twomlow et al. (2008), the recommended dimensions for planting pits are 0.9 m x 0.6 m (spacing), width of 0.15m; 0.15m depth and 0.15m length. Planting pits should be dug between September and October annually in the same position (Mupangwa et al., 2006) to create permanent markings. According to Getachew and Wondimu (2005) and Roose et al. (1999) the goal of zai pits in Yatenga are to capture rainwater, conserve soil moisture and capture organic matter brought in by Harmattan Winds in Burkina Faso. Zai pits were found to increase sorghum yield by up to 400% (Getachew and Wondimu, 2005) and they increase crop productivity in general (Sawadogo, 2011). Planting pits achieve fast rehabilitation of degraded land, especially in semi-arid climate.
The experiment was conducted at Vuravhi rural area in ward 8 of Chivi District. The rainfall for the area ranges from 350 mm to 500 mm per year. The average temperature of the area ranges from 27 °C to 32°C. The area is affected by long droughts and late onset of rainfall which leads to short growing season and moisture stress. Rainfall is also unevenly distributed causing some variation within the district. The area is dominated with sandy loam soils with poor water retention ability and associated with high leaching levels.
Before conducting the experiment soil samples were taken and analysed to determine pH and nutrients available. The soil pH was 5.83 and total nitrogen was 0.02% indicated poor nitrogen content. The experiment was conducted between December 2017 and April 2018. A sorghum variety Macia was planted and it is an open pollinated variety which yields between 3 to 6 t/ha. It takes on average 112 to 120 days to mature (Chikobvu, 2008).
The experiment was laid out as a completely randomised block with 6 treatments replicated three times to make 18 plots measured 4 m by 3 m. The treatments were; planting sorghum on tied ridges (TR), planting on planting pits (PP), and planting on conventional tillage (CT), planting sorghum in combination of cattle manure with tied ridges (TCM), planting pits (PCM) and conventional tillage (CCM). The ridges were made to be 0.30 m high and ties were 0.20 m high. There were six rows of sorghum in each plot planted at 0.9 m row spacing and 0.15 m plant spacing. Sorghum seeds were planted at a depth of 50 mm. Fertiliser was added during planting at a rate of 200kg/ha compound D and Ammonium nitrate was applied six weeks after planting at a rate of 100 kg/ha. Weeding was done using hoe and it was done three times before harvesting to control weed growth.
The following parameters were measured; grain yield, stover yield and grain moisture content at harvesting. Harvesting was done 140 days after planting by cutting the panicle from the plant using sharp knife and threshing seeds after harvesting. Stover yield was measured after cutting stover into smaller pieces from the net plot were harvesting was done. A digital scale was used and calculations were made using a calculator to transform yield to tonnes/ hectare.
Data was analysed using IBM SPSS statistics version 25 software for ANOVA. Different means were identified using least significant difference (LSD).
3. Results and discussion
Planting pits and cattle manure treatment yielded highest grain yield of 4.40 t/ha. Tied ridges and conventional tillage in combination with cattle manure yielded 4.30 and 3.81 t/ha grain. Conventional tillage was the control and yielded the lowest grain yield of 3.81 t/ha. The results show a significant different between the tree treatments (p < 0.05). The results are in Table 1 below. There was no significant different between grain yield from planting pits and tied ridges with cattle manure as indicated by same superscript. The significant different between insitu rainwater harvesting and conventional tillage in combination with cattle manure is due to high water retention ability by addition of cattle manure and tied ridges together with planting pits conserves moisture. Grain yield was low for all other three treatment; tied ridges (TR = 1.82 t/ha); planting pits (PP=1.94 t/ha) and conventional tillage (CT=1.80 t/ha). Although planting pits show highest yield but the results were not significantly different (p > 0.05). The PCM treatment yielded the highest stover yield of 8.35 t/ha and this show a significant different to yield of other treatment (p < 0.05). Stover yield of TCM and CCM were 8.20 and 7.81 t/ha respectively. Grain stover for other three treatments were 4.86 t/ha for PP treatment; 4.84 t/h for TR and 4.58 t/h for CT. These results show that there were no significant different between all these treatments as indicated with same superscript.