Published on International Journal of Agriculture & Agribusiness
ISSN: 2391-3991, Volume 2, Issue 2, page 115 – 121
Publication Date: March 13, 2019
Kugedera, A. T & Kokerai, L. K
Zimbabwe Open University, Department of Agriculture Management, Faculty of Agriculture
Great Zimbabwe University, Department of Livestock, Wildlife and Fisheries
Ministry of Agriculture, Lands, water and Climate, Department of Crop and Livestock
Low crop productivity has been caused by soil moisture stress and inherent soil fertility. The objective of the study was to assess the role of biomass transfer and integrated nutrient management on soil fertility and pearl millet yields. The experiment was set up as a randomised complete block design with five treatments replicated thrice. Soil samples were collected before initiation of experiment and after every harvest from 0-20 cm. Data was subjected to Analysis of Variance using IBM SPSS version 25. The results show that there was a significant different (p<0.05) of soil fertility parameters marked with an increase in total Nitrogen percentage, cation exchange capacity, percentage clay and decrease in percentage sand. Treatments with biomass transfer and cattle manure had the highest increases in all parameters and significantly higher than those with biomass transfer alone at p < 0.05. Panicle length was highest from treatments with cattle manure and ammonium nitrate fertiliser (29.7 cm for first harvest and 30.0 cm for second harvest) showing a significant different from those treatments with biomass transfer alone compared to other treatments. Pearl millet grain yields were higher from treatments with cattle manure and ammonium nitrate, 562kgha-1 for first harvest and 620 kg ha-1 for second harvest showing a significant different from all other treatments at p< 0.05. The use of cattle manure has shown an increase in soil fertility and pearl millet grain yields. It is recommended for smallholder farmers to use cattle manure amended with either biomass transfer or ammonium nitrate as this increases pearl millet grain yields about 514 kg ha-1 which most farmers used to get.
Keywords: Biomass transfer, soil fertility, integrated, nutrient management & pearl millet.
Inherent soil fertility has been the major cause for poor crop production in arid and semi-arid areas around the world (Branca et al., 2011). This has been a consequence of increased soil erosion, poor farming methods and low addition of nutrients to the soil. Most farmers in smallholder areas are poor resource (Chikowo, 2004) with most farmers unable to buy inorganic fertiliser and some do not even have cattle to produce manure for use (Fatondji et al., 2006). This has worsened food insecurity in smallholder farming areas in arid and semi-arid regions that face erratic rainfall associated with severe mid-season drought. This all leads to land degradation which is a major factor contributing to poor crop production and food insecurity (Saidou et al., 2010b).
Pearl millet (Pennisetum glaucum (L)) is one of the most important cereal crops in arid and semi-arid areas of Zimbabwe. Grain yields of pearl millet have been declining for years in arid and semi-arid areas of Zimbabwe, yielding around 500kg ha-1 (Chikobvu, 2008). This has also been noted in Mali where grain yield of 514kg ha-1 has been recorded (DNA, 2011), with 50 to 500 kg ha-1 recorded in Niger (Manyame, 2006). Pearl millet production had been greatly hindered by low rainfall associated with severe mid-season droughts, high surface runoff and monoculture. Additions of inorganic fertilisers supplemented with cattle manure have a great impact on improving pearl millet production. Farmers can also use biomass transfer to add nutrients in the soils. Biomass transfer is the application of leafy materials from legume trees such as Sesbania sesban, Leucaena leucocephala and Gliricidia sepium which contains high levels of nitrogen. Incorporation of biomass in soils has a great increase in soil fertility (Nyamadzawo et al., 2008a), thus increasing soil organic matter, increase infiltration (Nyamadzawo, 2008a) and water retention. This also improves cation exchange capacity of the soil (CEC). Addition of cattle manure integrated with inorganic fertilisers had known to have significant increase in nitrogen content (Ngetich et al., 2011), improve maize grain yields (Balemi, 2012; Bayu et al., 2005). The objective of the study was to assess the role of biomass transfer and integrated nutrient management in improving soil fertility and pearl millet yields.
2.1 Site location
The experiment was up in the experimental plot at Farm 102 Zvinyaningwe in Mashava (Masvingo West), Masvingo Province, Zimbabwe. Located within the latitude 20° 2ʹ 43ʺ S and longitude 30° 40ʹ 29ʺ E in the south eastern part of Zimbabwe. The experimental plots were located in the semi-arid areas of Zimbabwe where rainfall received is between 450 mm to 550 mm per annum. The area is characterised with high temperatures ranging from 18-32°C. The soils of the experimental site were sandy loam soils as indicated in Table 1.
2.2 Land preparation and treatments
The trials were established at one site during the short rain season (December 2016 to May 2017) and long rain season (October 2017 to April 2018). Land was prepared using ox-plough to approximately a depth of 15 cm. The size of each plot was 3m x 3 m with spacing of 75cm between the rows and 20 cm within the rows. PV3 sorghum seeds obtained from SEDCO Seed Unit were used. More seeds were placed within the line and thinned three week after emergence. Cattle manure was applied at planting and was placed in furrows prepared using hand hoes. Fertilizers were pre-weighed for each plot before going to the field and applied using dollop cups to ensure uniform distribution within the plot. Weeding was done two times using hand hoe and cultivator. The main plot factor were pearl millet planted on site with biomass transfer (PMB), cattle manure (PMCM), biomass transfer + cattle manure (PBCM), cattle manure + inorganic fertiliser (PCMF) and biomass transfer + inorganic fertiliser (PBF). Cattle manure was applied at a rate of 2500kg ha-1 and ammonium nitrate was applied at a rate of 100kg ha-1. The experiment was set up as a randomised complete block design (RCBD) with each treatment replicated three times to give a total of 15 plots measuring 3m x 3 m and a net plot of 2m x 2 m. soil sample were collected randomly from the field site at the depth of 0-20 cm before cultivation and after harvesting were collected from three points from each plot. These soil samples were air dried and sieved with a 2mm mesh sieve and used to analyse selected soil chemical properties and core samples were used to analyse physical properties of the soil. Data was subjective to analysis of variance for RCBD using SPSS IBM 25 and statistical significance treatments of means were estimated using least significance difference (LSD).
The results presented in Table 1 shows soil chemical and physical properties before the experiment had started. The soil was slightly acidic with low organic carbon, total nitrogen, CEC and high sand, low clay and average silt content.
3.1 Effects biomass transfer and integrated nutrient management on soil fertility parameters
After two years of experiment the results show a significant (P<0.05) increase in soil fertility parameters such as nitrogen content, pH, clay content and CEC of the soil. Even soil moisture content showed a significant increase due to improved soil organic matter content. Treatments with a combination of biomass transfer and cattle manure showed significantly high effect on both soil chemical and physical properties after 2nd year of harvest. Total nitrogen increased from 0.27 % to 0.34% after first harvest and from 0.34% to 0.68% in the second year. Phosphorous increased from 4.18 mg kg-1 to 4.97 mg kg-1 after 1st and to 5.17 mg kg-1 after 2nd harvest. CEC increased from 2.42 cmolc kg-1 to 2.82 cmolc kg-1 after the first harvest. A combination of biomass transfer and ammonium nitrate had low improvements for example total nitrogen increased from 0.27 % to 0.29% after the first harvest and increased from 0.29 % to 0.32% after 2nd harvest. CEC also showed low increases from 2.42 cmolc kg-1 to 2.58 cmolc kg-1 after 1st harvest. Table 2 below show the results on the effects of biomass transfer and integrated nutrient management on soil chemical and physical properties. All the treatments showed a decrease in percentage sand, silt and an increase in percentage clay. The results show a significant increase (P< 0.05) in soil chemical and physical properties. Soil macroorganisms were also noticed in the soil after 1st and 2nd harvest.
3.2 Effects biomass transfer and integrated nutrient management on panicle length and pearl millet grain yield
The results show that panicle length was highest from treatments applied cattle manure and ammonium nitrate with a length of 29.7 cm as compared to treatments applied biomass transfer only, having 25.0 cm. panicle length obtained from treatments with biomass transfer only was significantly different (P<0.05) from plots applied biomass transfer + cattle manure and those applied with cattle manure and ammonium nitrate all after first harvest. The results of panicle length obtained during 2nd season harvest was significantly different (P<0.05) between plots with PMB, PMCM and between PBCM and PCMF. Grain yield was highest from PCMF plots with 562 kg ha-1 and lowest from PMB treatments with a mean of 450 kg ha-1. There was a significant different between yields obtained from all treatments biomass transfer at p < 0.05 during first season harvest (Table 3). Grain yields obtained during 2nd season were significantly higher than yields obtained from first harvest at p <0.05. Treatments applied cattle manure showed significant increase in grain yields. Treatments applied with ammonium nitrate produced grain yields which were significantly different at p< 0.05, that is, PCMF produced 620 kg ha-1 compared to 560 kg ha-1 obtained from PBF treatments as mean grain yields (Table 3).