Many views, paradigms and concepts have been advocated in recent decades on soil fertility and soil conservation across the globe in order to provide sustainable solutions to the rising food and nutrition insecurity while preserving the natural resource base. Meanwhile, food and nutrition security in Sub-Saharan Africa (SSA) is mainly achieved through smallholder farming systems that are characterized by poor and declining soil fertility, which often leads to low crop yields and low income. Hence, a field trial was established to evaluate the impact of integrated soil fertility management (ISFM) practices on tomato yield and the farm-scale income in smallholder farming systems. The ISFM trial comprised a control with no input, mineral fertilizer, and organic treatments comprising sole Mucuna and Tithonia biomasses as well as their combination ( Mucuna + Tithonia). Generally, tomato performance was better with organic plant biomass amendments, with significantly higher (P < 0.001) tomato yield for Mucuna + Tithonia and sole Tithonia, followed by sole Mucuna and mineral fertilizer compared to the control. Meanwhile in comparison to the control, Mucuna + Tithonia and sole Tithonia recorded 3.5 and 3.4 t ha -1 more yield, respectively, which was about twice the additional yield for sole Mucuna and mineral fertilizer with 1.8 and 1.5 t ha -1, respectively (Tukey’s HSD, P < 0.05). Similarly, the farm-scale income increased significantly (P < 0.001) for organic plant biomass, and it was most pronounced for Mucuna + Tithonia and sole Tithonia, followed by sole Mucuna and mineral fertilizer, as compared to the control (Tukey’s HSD, P < 0.05). A positive Spearman Rank Correlation was recorded between the ISFM treatments and tomato yield or the farm-scale income (r = 0.76, P < 0.05), and between tomato yield and the farm-scale income (r = 0.99, P < 0.05). These results imply that smallholder farmers in SSA can effectively use the combination of Mucuna + Tithonia biomass materials or their sole applications as basal mulch to improve tomato production. Thus, these organic amendments could be an alternative and sustainable integrated soil fertility management strategy to boost tomato production and farm-scale income without jeopardizing the sustainability of the environment. However, this requires more efforts to adapt the different ISFM techniques to the specific needs of smallholder farmers, coupled with effective dissemination strategies that facilitate knowledge transfer and technology adoption.
Sub-Saharan Africa (SSA) accounts for about 9% of global population with high food and nutrition insecurity that is partly due to poor and declining fertility status of the largely acid soils, with nitrogen and phosphorus as the most limiting mineral elements [
The concept of integrated soil fertility management (ISFM) is widely encouraged in SSA, and it is largely considered as a set of agronomic practices adapted to local conditions to maximize nutrient use efficiency and improve crop productivity. The ISFM techniques incorporate mineral fertilizer and locally available inputs (i.e. lime and rock phosphate) with organic matter (i.e. crop residues and compost) to replenish soil nutrients, improve agronomic efficiency and crop production [
Despite the agronomic importance of different ISFM strategies, their adoption by smallholder farmers has been relatively slow due to a combination of factors, which include poor understanding of the economic benefits, high labour demand and poor technology promotion strategies. Furthermore, most ISFM studies have mainly focused on the direct impact of ISFM on soil restoration parameters rather than the crop productivity and potential economic benefits for farmers. Although many studies have been conducted on the importance of mineral fertilizer and organic amendments as well as on their combinations in various ISFM strategies, few studies have been devoted to the potential benefits of combining different plant biomass materials in ISFM. To the best of our knowledge, there is no specific investigation on the potential benefits of combining Mucuna and Tithonia biomass materials as basal mulch for integrated soil fertility management in horticultural systems. Hence, this participatory ISFM field trial was intended to adapt and evaluate the potential of combining two plant biomass materials (Mucuna + Tithonia) as basal mulch to improve soil fertility and plant nutrition, so as to improve tomato yield and farm-scale income for smallholder farmers in Cameroon. Therefore, it is hypothesized that the interaction of organic mulches of Mucuna + Tithonia will improve tomato yields and farm-scale income as compared to sole Mucuna or Tithonia biomass applications and mineral fertilizer amendments or the control without any input.
This study was conducted on a smallholder farm in Lysoka-Buea, located at the foot of mount Cameroon, south- western Cameroon. The area is situated between latitudes 4˚3'N and 4˚12'N of the equator and longitudes 9˚12'E and 9˚20'E. The soils are mostly derived from volcanic rocks and generally fertile but have poor moisture retaining capacity [
The field site had been under intensive commercial banana production by the Cameroon Development Corporation (CDC) until 2009. The site was further used for smallholder intercropping system to cultivate subsistence crops like maize (Zea mays), (Manihot esculenta), okra (Abelmoschus esculentus), ginger (Zingiber officinale), beans (Phaseolus spp) and cowpeas (Vigna unguiculata) until 2013. In 2014, the site was cleared manually using cutlasses and partitioned into experimental plots of 20 m2 (5 × 4 m) with a 1m buffer zone between plots. All the experimental plots were tilled manually using hoes and a cover crop (Mucuna cochinchinensis) was planted in March 2014, at 30 × 30 cm spacing and allowed to fallow for one year in order to establish a homogeneous soil. The Mucuna was harvested at maturity in March 2015, and Mucuna seeds and shells were separated from the biomass (leaves and stems). The biomass and seeds were sun-dried separately and preserved at room temperature for eventual use as basal mulch and propagation materials, respectively.
Hybrid tomato (Lycopersicon esculentum L.) seeds (F1 Cobra 26; TECHNISEM® France) were purchased from a local agro-shop in Buea Cameroon. The F1 Cobra 26 is determinate with very good vigour, and combines tolerance/resistance to Tomato Yellow Leaf Curled Virus (YLCV) and Bacterial Wilt (Ralstonia solanacearum), which enable very good productivity, and viability to the Sahelian and tropical areas. It also has very good maturity with the first harvest from 65 days after planting, and produces square fruits of medium sizes (80 - 90 g) with uniform coloration. In addition, the fruits have good firmness that allows for good postharvest conservation.
The F1 Cobra 26 seeds were pre-germinated on a nursery bed of 2.5 × 1 m close to the experimental plots, which was prepared by clearing the site with a cutlass and the soil tilled manually using hoes. The tomato seeds were sown on the 26th of March 2015 on the nursery bed at an inter-row spacing of 15 × 15 cm. Vigorous tomato seedlings were transplanted from the nursery bed to the experimental plots on the 21st April 2015. The tomato seedlings were planted at a distance of 1 × 0.5 m on the experimental plots of 20 m2 (5 × 4 m), with one plant per stand, giving a total of 35 stands per plot. In order to facilitate acclimatisation of tomato plants after transplanting, moisture was immediately provided for each plant via irrigation with tap water, while subsequent moisture was provided by rainfall. Each tomato plant received three litres of water, applied manually by pouring onto the plant-soil interface using watering cans. All 750 plants on the experimental site were staked manually with 1 m wooden sticks and the plants attached firmly to the stakes on the 15th of May 2015 using ropes.
The field trial was established as a randomized block design with four replicates per treatment. There were five treatment variables comprising a control with no input, mineral fertilizer, and two organic biomass mulches of Mucuna cochinchinensis and Tithonia diversifolia (Mexican sunflower), as well as their combination (Mucuna + Tithonia, at 1:1). Organic mulch materials were applied as single basal dose at the rate of 10 kg DW per plot (20 m2) that is equivalent to 5 t ha−1 [
In order to facilitate technology appraisal and adoption, a participatory management approach was employed involving the local beneficiary smallholder farmers at all stages of production from field preparation and planting, to harvesting and marketing of produce. Apart from the initial irrigation performed immediately after transplanting of seedlings to the experimental plots, plant growth and performance depended entirely on rain-fed system based on the local rainfall regime. Meanwhile, management practices for weeds, pest and diseases were the same for all treatment plots. Before transplanting the tomato seedlings, the entire field was thoroughly weeded manually using cutlasses and hoes on 16/04/2015. After transplanting of the tomato seedlings, the field was monitored regularly for the emergence of weeds and when necessary, weeding was performed manually using hoes on 14/05/2015, 10/06/2015 and 02/07/2015. In order to maintain plant health and crop damage by pests and diseases within acceptable economic levels, frequent scouting was done for all plots to monitor the emergence of insect pests and diseases. When necessary, all plots were sprayed with appropriate doses of fungicide (Mancozan super; SCPA SIVEX International® France) or insecticides (Garmaline 80, AGROMAF® Cameroon; Cigogne 360, SCPA SIVEX International® France; and Acarius, SAVANA-Horizon Phyto Plus® Cameroon).
Since the main focus of this particular investigation was on the tomato yield and potential income gains for the resource-poor smallholder farmers, data on the soil dynamics were not considered in this study. A total of nine tomato harvests were performed within thirty-two days, starting on the 20th of June 2015 and ending on the 27th of July 2015. The tomato fruits were harvested twice a week from each treatment plot, counted and weighed separately using a top loading balance. The harvested tomato fruits were sold in the local markets and the market value was used to determine the farm-scale income generated by each treatment. The farm-scale income was calculated as the total income generated after computing the difference between the total tomato sales and the cost of inputs for the respective plots (i.e. farm-scale income = total tomato sales ? total cost of inputs). In order to evaluate the direct impact of ISFM treatments, we determined the additional tomato yields and farm-scale income derived from each ISFM treatment by calculating the difference between each ISFM treatment and the control (i.e. additional yield or income = ISFM treatment ? control). All treatment means were computed and the data sets were subjected to statistical analysis using STATISTICA 9.1 for Windows [
The impact of ISFM techniques was mainly evaluated from the perspective of potential benefits for smallholder farmers (i.e. crop performance and economic gains) so as to provide greater insight that may facilitate ISFM technology adoption by resource-poor farmers in SSA, since technology adoption is based on knowledge and proven efficacy as well as potential economic gains.
Tomato performance was assessed as yield (fresh fruit weight) and the thousand fruit weight for each treatment. The average tomato yield measured as total fresh fruit weight ranged from 9.7 to 13.2 t ha−1 across the different treatments (
The potential for better crop performance and greater economic gains largely drive the interest of smallholder farmers in adopting new technologies against traditional practices. The total farm-scale income ranges between 7223 and 8520 US Dollar (3,128,663 and 4,260,136 FCFA) across the different treatments. The total income
Tomato performance | ||
---|---|---|
Treatments | Yield [t ha−1] | 1000 Fruit weight |
Control | 9.7 ± 0.3 c | 68.6 ± 16.6 a |
Mineral fertilizer | 11.2 ± 0.5 b | 68.3 ± 16.6 a |
Mucuna | 11.5 ± 0.4 b | 76.1 ± 16.4 a |
Tithonia | 13.1 ± 1.2 a | 70.4 ± 10.1 a |
Mucuna + Tithonia | 13.2 ± 0.2 a | 68.2 ± 10.0 a |
was significantly higher for the organic mulches (P < 0.001), and most pronounced for the interaction of Mucuna + Tithonia biomass and the sole Tithonia treatments, followed by the sole Mucuna biomass and mineral fertilizer treatments as compared to the control (Tukey’s HSD, P < 0.05;
According to The Economist [
Crop yield is determined by a combination of environmental factors and farm management practices that in turn
Farm-scale income | ||
---|---|---|
Treatments | FCFA | US Dollar |
Control | 3128663 c | 6257 c |
Mineral fertilizer | 3611854 b | 7224 b |
Mucuna | 3688359 b | 7377 b |
Tithonia | 4227923 a | 8456 a |
Mucuna + Tithonia | 4260136 a | 8520 a |
influence soil fertility and plant nutrition. Despite applying 180 kg ha−1 mineral fertilizer that is more than twice the 87 kg ha−1 applied in developed nations [
Besides the influence of Mucuna and Tithonia on soil properties, they possibly enhanced both root and shoot physiological and morphological developments, which in turn increased productivity. This is consistent with greater root production and lifespan induced by compost and mulching as compared to mineral fertilizer [
Although ISFM considers combining appropriate micro doses of mineral fertilizer either solely or in combination with locally available organic materials as an important strategy for soil fertility improvement, the use of different organic inputs either solely or combined would be a more sustainable ISFM alternative. Accordingly, the best tomato yield was recorded with the combined biomass of Mucuna + Tithonia and the sole Tithonia biomass application as compared to sole Mucuna, mineral fertilizer or the control. This is consistent with [
The adoption of integrated soil fertility management technologies largely depends on the confidence of smallholder farmers towards these techniques, which is mainly determined by the crop production and income gained. However, inadequate knowledge on the best-bet ISFM options for specific crops and lack of confidence in the economic returns induces laxity of adopting such technologies by smallholder farmers. Thus, smallholder farmers in SSA have not experienced a significant decrease in yield gap between the actual and expected production per unit area of cultivable land. This is partly due to inadequate supply of the required inputs and high cost, poor technology adoption and lack of knowledge on potential benefits [
A plethora of views, paradigms and concepts on sustainable agriculture and natural resource management have arisen in recent decades, which are intended to boost agricultural productivity and provide sustainable solutions to one of the earth’s most pressing challenges of preserving the natural resource base. These include integrated soil fertility management, conservation agriculture, integrated nutrient management, organic agriculture, and integrated natural resource management [
Besides the proven efficacy for Mucuna and Tithonia biomass for independently improving soil physical, chemical and biological properties, the Mucuna + Tithonia biomass combination was comparable to sole Tithonia, which was better than sole Mucuna biomass that displayed a comparable performance with mineral fertilizer in terms of tomato yield and farm-scale gains. This makes Mucuna + Tithonia biomass a viable and important ISFM alternative for sustainable soil fertility management that is commensurate with the existing plethora of views, paradigms and concepts on sustainable agriculture and natural resource management. Hence, smallholder farmers can effectively adopt Mucuna and Tithonia biomass applied in combination or solely, to improve net productivity and farm-scale income without any negative externalities. However, this requires more efforts to adapt different techniques to the specific needs of smallholder farmers, with effective dissemination strategies that facilitate technology adoption. Although Tithonia is widely distributed on abandoned lands and roadsides in Cameroon, it can be planted on farm boundaries to enhance availability and reduce the associated labour and transport costs. Meanwhile, Mucuna biomass can be harvested from fallow sites where they are cultivated as green manure cover crops. Overall, this alternative soil fertility management technique has multiple advantages on soils including decontamination, mineralization, conservation, increased soil biota, erosion control and water conservation within the broader context of sustainable agriculture, and the specific concept of integrated soil fertility management in smallholder farming systems. Nonetheless, more in situ based studies are necessary to provide greater insights on the specific impacts of combining Mucuna and Tithonia biomass materials on the dynamics of soil biota (i.e. microbial abundance and diversity, food web ecology or, mycorrhiza dynamics, etc.). Thereby providing a holistic view of soil microorganism and integrated soil fertility management that improves soil fertility and plant nutrition, leading to greater crop productivity and income for farmers.
Funding for this study was provided by Research Grant of the Faculty of Agriculture and Veterinary Medicine― FAVM, University of Buea, and supported by the Research and Modernization Allowance of the Ministry of Higher Education of Cameroon. We are grateful to Ngu George, Bezeng Fidelis and Lyonga Efunganyi (FAVM, University of Buea) for their assistance with field management, and Asongwe Joseph “General” who secured the experimental site.
ChristopherNgosong,PriscillaM. Mfombep,AkemeC. Njume,AaronS. Tening, (2015) Integrated Soil Fertility Management: Impact of Mucuna and Tithonia Biomass on Tomato (Lycopersicon esculentum L.) Performance in Smallholder Farming Systems. Agricultural Sciences,06,1176-1186. doi: 10.4236/as.2015.610112