Open Access Original Research Article

Assessment of Soil Fertility Status for Bambara Groundnut Production in South-eastern Tanzania

John J. Tenga, Johnson M. R. Semoka, Ernest Semu, Balthazar M. Msanya

International Journal of Plant & Soil Science, Page 1-13
DOI: 10.9734/IJPSS/2018/41970

Intensive farming practised in the agro-ecological zones of Makonde plateau (C2) and Inland plain (E5) of south-eastern Tanzania without proper soil management has led to nutrient depletion. The objective of the study was to assess the fertility status of soils in Bambara groundnut growing areas of south-eastern Tanzania. Twenty-two farmers' field sites were sampled and composite samples of top soil at 0 – 20 cm depth were collected for physical and chemical analysis. The results indicate that the soils in the study area are sandy loam (64%), loamy sand (27%) and sandy clay loam (9%). About 28% of the soils in the study area had very low CEC values (< 6 cmol (+) kg soil). Soil pH was strongly acidic to moderately acidic (≤ 5.5) and slightly acidic (≥ 6.0) in the C2 and E5 agro-ecological zones, respectively. Total N was very low (< 0.1%) and organic carbon was very low to low (< 0.6%). Low levels of available P (<10 mg/kg), inadequate S (SO4-S) levels (< 10 mg/kg) were observed. The exchangeable K in the C2 zone was very low to low (< 0.05 cmol(+)/kg) while E5 zone had medium K level. The calcium level of C2 was low to medium (0.2 – 2.5 cmol(+)/kg) whereas that of E5 was medium to high (0.6 – 5.0 cmol(+)/kg). The exchangeable Mg2+ levels were very low to low (< 0.2 cmol(+)/kg) while Na+ was < 0.30 cmol(+)/kg soil indicating no sodicity problem. For > 90% of the studied soils extractable Zn was below critical level of 0.6 mg/kg. All soils had adequate extractable Fe whereas > 70% of the soils had high (> 5 mg/kg) extractable Mn. The study area generally indicated low fertility status in terms of N, P, K, S, Mg and Zn, calling for proper management for improving crop production.

Open Access Original Research Article

Vermicompost Potential of Common Earthworms (Eudrilus eugeniae) and Red Wiggler (Eisenia fetida) Worm on the Decomposition of Various Organic Wastes

Zerihun Getachew, Tigist Adisu, Lejalem Abeble, Bekele Anbessa

International Journal of Plant & Soil Science, Page 1-13
DOI: 10.9734/IJPSS/2018/42986

Purpose: To evaluate the vermicomposting potential of Eudrilus eugeniae and Eisenia fetida earthworms on decomposition of various organic wastes through worm growth and production of nutrient rich vermicompost.

Methods: Two local Eudrilus eugeniae earthworms (Debrezeit and Keshmando) and commercial Eisenia fetida earthworm were evaluated using different agricultural (maize and haricot bean straws), urban (khat, food and fruits peels) and industrial (bamboo) wastes. Seven types of wastes (each mixed with cow manure) were used and with three earthworm types which gave a total of twenty one treatments. The experiment was laid out in a factorial completely randomised design (CRD).

Results: Earthworm growth and nutrient composition of the final vermicompost was significantly (p <0.05) affected by the main and interaction effects of worm and type of organic feed. High numbers of cocoons and worms, as well as worm biomass, were recorded with Keshmando and Eisenia fetida when fed into khat and maize straw, while the least count and biomass of worms were recorded in an industrial waste feed. The chemical compositions of vermicomposts of all earthworm types produced for each substrate were more than that of their respective initial feed mixture. A significant increase in available plant nutrients and a rapid decomposition of dissolved organic C content were observed in all the vermicompost treatments. The highest % N (0.84) with decreased C: N ratio was found in Debrezeit with khat substrate, while the highest P (370 ppm) and K (12.6 g/kg) contents were found in Eisenia fetida with maize straw.

Conclusion: Results clearly indicated that the type of substrate significantly influenced worm growth and quality of the end product. Worms showed no drastic difference in a decomposition of wastes which exhibited the potential and candidature of local earthworms with Eisenia fetida for vemicomposting. Further, the study revealed the suitability of maize straw for better worm growth and production of nutrient-rich vermicompost

Open Access Original Research Article

Response of Growth and Grain Yield of Amaranth (A. hypochondriacus) to Combined Manure and Inorganic Fertiliser Pellets and Non-pellets

J. H. Love, R. O. Nyankanga

International Journal of Plant & Soil Science, Page 1-10
DOI: 10.9734/IJPSS/2018/43110

Grain amaranth (Amaranthus hypochondriacus L) has high potential to substitute expensive animal protein because of its high nutritional value and is potential to reduce protein malnutrition in Kenya. However, its production and consumption are low.  Nitrogen fertilisation is among the most important factors limiting productivity. Most farmers use manure and little or no fertiliser. Manures alone cannot meet crop nutrient demand over large areas because of the limited quantities, low nutrient content and the high labour requirement. Manure – fertiliser augmented pellets have been suggested as an improved alternative. This study investigates the effects of pellet fertiliser, produced by mixing calcium ammonium nitrate (CAN) and dry cow dung manure on growth and grain yield of Amaranthus hypochondriacus L over a period of two years. The experiment was laid as randomised complete block design (RCBD) with split plot arrangement and replicated three times. The treatments were different combinations of organic and inorganic fertiliser; 0 percent inorganic N and 100 percent organic N, 25 percent inorganic N and 75 percent organic, 50 percent inorganic N and 50 percent organic N, 75 percent inorganic N and 25 percent organic N 100 percent inorganic and 0 percent organic. The controls consisted of non-pelleted combinations and a non fertiliser treatment. All the pellet fertiliser treatments had higher dry matter weight, 1000 seed weight and grain yield compared to control and non-pelleted treatments. Fertiliser combination of 75 percent organic N and 25 percent inorganic N had the highest grain yield while fertiliser combination of 25 percent organic and 75 percent inorganic recorded the lowest grain yield compared to the other combinations. The use of pellet fertiliser increased grain yield and could be used as an alternative, however, recommendation for adoption should be done after economic analysis.

Open Access Original Research Article

Response of Quality Protein Maize (Zea mays L.) to Nitrogen Rates and Plant Population in Ambo, Central Ethiopia

Girma Abera, Haji Kumbi

International Journal of Plant & Soil Science, Page 1-12
DOI: 10.9734/IJPSS/2018/43160

Aims: Quality protein maize (QPM) is one of the major food crops in Ethiopia. However, agronomic management practices were not properly developed for QPM production in the highland areas of Ambo, central Ethiopia.

Methodology: A field experiment was conducted at Ambo Crop Protection Research Center Farm to investigate the effects of nitrogen and plant population using hybrid QPM variety, AMH-760Q.

Study Design: The treatments consist of four nitrogen rates (0, 46, 92 and 138 kg N ha-1) and four plant populations (44,444, 53,333, 66,666 and 88,888 plants ha-1) arranged in split plot design with three replications.

Results: The nitrogen rates and plant population were significantly (P = .05) influenced most of QPM parameters. Increase in both nitrogen rates and plant population delayed days to tasseling, silking and physiological maturity, and also increased plant height, stem diameter and leaf area index. The application of nitrogen increased ear diameter, ear length, number of ears per plant, number of seeds per ear, thousand seed weight, straw and grain yields. Similarly, plant population at 66,666 plants ha-1 improved most yield components, straw and grain yields of QPM. The straw, grain and total N uptake were also increased in response to N application. The interaction of nitrogen and plant population also significantly (P = .05) affected straw and grain yields.

Conclusion: The results demonstrate that the application of 92 and 138 kg N ha-1 to 66,666 plants ha-1 resulted in higher straw and grain yields. Also if there is a need for high straw production for livestock feed, 88,888 plants ha-1 with 92 kg N ha-1 could be recommended.  This implies that QPM straw and grain yields could be maximized through proper matching plant population and N fertilizer rates.

Open Access Original Research Article

Modelling Nutrient Dynamics and Maize Yields under Different Cropping Systems and Organic Amendments Using APSIM in Central Kenya

O. H. Ndukhu, G. R. Wahome

International Journal of Plant & Soil Science, Page 1-16
DOI: 10.9734/IJPSS/2018/16201

A simulation study was carried out using APSIM model to assess the maize yield and soil nutrients to changes in temperatures and rainfall in Kabete and Kiserian areas of central Kenya. To obtain data for model calibration and validation, on-station (Kabete) and on-farm experiments (Kiserian) were set out during the short rain season of 2013. The experimental design was a randomized complete block (RCBD) with a split-plot arrangement where the main plots were three cropping systems; monocropping, intercropping and crop rotation and the split plots were farmyard manure (FYM) and Minjingu Rock Phosphate (MRP), and a control. The effect of the changes in rainfall and temperature on maize yields was considered, i.e. current temperature combinations in accordance to the International Panel on Climate Change projections.  The model performed better for Kabete (ME=0.6) than Kiserian (ME=0.9). Simulations of crop rotations correlated most (R2=0.48) with observed results at Kabete and Kiserian. Simulations of the intercrops correlated favourable with coefficient of determination (R2) values of >0.4 showing a reasonable relationship between observed and simulated values. However, mono-crop simulation varied highly from observed yields (R2<0.3). The APSIM simulated matched well with the observed data in the trial; root means standard error (RMSE) 2.07 for Kabete and 2.49 for Kiserian. Maize-chickpea cropping systems with application of FYM and MRP gave better yields as they resulted in higher predicted yields compared to the monocrop. The impacts of climate change and variability, i.e. reduced rainfall and increased temperatures that led to lower maize yields. These rainfall and temperature regimes call for the development of appropriate adaptation techniques.