Peter Opala | Maseno University (original) (raw)
Papers by Peter Opala
Agricultural Reviews
The use of locally available phosphate rock (PR) has often been proposed as a cheaper alternative... more The use of locally available phosphate rock (PR) has often been proposed as a cheaper alternative to the more expensive superphosphate fertilizers to alleviate severe phosphorus deficiencies that threaten food security in East Africa. Extensive research has therefore been conducted in the region over the years focusing on the PR sources, their reactivity, agronomic effectiveness and the economics of their use and adoption. The agronomic effectiveness varied with the type of PR, the site, seasons and crop. Minjingu PR was the most promising among the PRs for direct application but others such as Panda, Sukulu and Busumbu PR were largely ineffective. The financial returns due to use of PR ranged from negative to positive but in many cases were economically not attractive. The adoption of PR use among farmers was dismal with the unavailability of the PR in the market and high cost, paradoxically being cited as the main constraints to its adoption. To enhance the chances of adoption, it...
<p>SDW, N concentration and SE of representative isolates in Kakamega, Kenya.</p
<p>SDW, N concentration and SE of representative isolates in Kisumu, Kenya.</p
Maize production in western Kenya is often limited by deficiencies of nitrogen and phosphorus. We... more Maize production in western Kenya is often limited by deficiencies of nitrogen and phosphorus. We assessed the effectiveness of Tithonia diversifolia green manure (tithonia), farmyard manure (FYM) and urea as sources of nitrogen (N) for maize when inorganic phosphorus (P) fertiliser was either broadcast (BR) or spot-placed in the planting hole (SP) for two consecutive seasons; October to December of 1998 and April to August of 1999 at two sites; Nyabeda and Khwisero in western Kenya. A randomised complete block design with four replications was used. Maize yields were higher at Nyabeda and responded to P application better than at Khwisero. At the same N rate, tithonia and FYM were as effective as urea in increasing maize yields at both sites. There were no significant differences in maize yields when phosphate fertiliser was either BR or SP regardless of the N source used in the first season. However, in the second season, the residual yields for the BR treatments were consistently...
The use of phosphate fertilizers and lime to mitigate P deficiencies and Al toxicities in Kenya h... more The use of phosphate fertilizers and lime to mitigate P deficiencies and Al toxicities in Kenya has not been effective due to their high cost. Organic materials (OMs) are therefore being tested as cheaper alternatives but there are knowledge gaps on how they interact with soil to increase crop yields in acid soils. The effect of two OMs; farmyard manure (FYM) and Tithonia diversifolia (tithonia) green manure, and agricultural lime, each when applied alone or in combination with triple superphosphate (TSP), on selected soil chemical properties related to fertility and nutrient uptake by maize, was tested in a greenhouse experiment. Only the lime and FYM treatments significantly increased the soil pH. Lime was the most effective amendment in reducing the exchangeable Al followed by tithonia and FYM but TSP when applied alone did not reduce exchangeable acidity. The OMs and lime, when applied alone or in combination with TSP reduced the P sorption capacity of the soil but TSP on its ow...
International Journal of Plant & Soil Science, 2015
ABSTRACT The influence of two organic materials (OMs); Tithonia and FYM and inorganic materials; ... more ABSTRACT The influence of two organic materials (OMs); Tithonia and FYM and inorganic materials; triple superphosphate (TSP) and Minjingu phosphate rock (MPR) and Busumbu phosphate rock (BPR), when applied alone or in combination, on P sorption at two sites, Kakamega and Bukura, in western Kenya was investigated. The soil at Bukura was a Ferralsol while that at Kakamega was a Cambisol. A randomized complete block design with 3 replications was used. All the P inputs were uniformly broadcast on the plots and then incorporated into the top soil (0-15 cm) in April 2007. Soils were sampled at 4 and 9 weeks after incorporation of phosphorus inputs (WAI) from each of the treatments and the soil P sorption characteristics determined. The equilibrium P concentration which represents the amount of P in the equilibrium solution at zero P sorbed was < 0.2 mg P L
ISRN Agronomy, 2012
We tested the effects of two organic materials (OMs) of varying chemical characteristics that is,... more We tested the effects of two organic materials (OMs) of varying chemical characteristics that is, farmyard manure (FYM) and Tithonia diversifolia (tithonia), when applied alone or in combination with three inorganic P sources, that is, triple superphosphate (TSP), Minjingu phosphate rock (MPR), and Busumbu phosphate rock (BPR) on soil pH, exchangeable acidity, exchangeable Al, and P availability in an incubation study. FYM and tithonia increased the soil pH and reduced the exchangeable acidity and Al in the short term, but the inorganic P sources did not significantly affect these parameters. The effectiveness of the inorganic P sources in increasing P availability followed the order, TSP > MPR > BPR, while among the OMs, FYM was more effective than tithonia. There was no evidence of synergism in terms of increased available P when organic and inorganic P sources were combined. The combination of OMs with inorganic P fertilizers may, however, have other benefits associated wit...
Nutrient Cycling in Agroecosystems, 2009
Maize production in western Kenya is commonly limited by P deficiencies and aluminum phytotoxicit... more Maize production in western Kenya is commonly limited by P deficiencies and aluminum phytotoxicity. Due to high costs of imported fertilizers and lime, focus is now shifting to solutions that utilize local resources. We tested the effect of three inorganic P sources i.e., triple superphosphate (TSP), Minjingu phosphate rock (MPR) and Busumbu phosphate rock (BPR), each applied in combination with two organic materials (OMs) i.e., farmyard manure (FYM) and Tithonia diversifolia green manure (tithonia), or with urea on soil chemical properties related to soil acidity, P availability and maize yields for three consecutive seasons in western Kenya. The OMs and inorganic P sources were applied to provide 20 and 40 kg P ha-1 respectively in their combination. Where urea was used, the inorganic P sources were applied at 60 kg P ha-1. Maize did not respond to application of TSP, MPR or BPR with urea in the first two seasons. However, after three seasons, maize significantly responded to application of MPR with urea. FYM was more effective than tithonia in increasing the labile inorganic P pools but it gave lower maize yields than tithonia which was more effective in reducing the exchangeable Al. It appears that the ability of an OM to lower the exchangeable Al is more important in increasing maize yields than its ability to increase P availability. The effectiveness of the inorganic P sources in increasing maize yields followed the order of their effectiveness in increasing available P, i.e., TSP [ MPR [ BPR, once Al phytotoxicity was reduced by application of tithonia but the difference between TSP and MPR was not significant. The extra maize yield obtained by the additional 40 kg P ha-1 from the inorganic P sources was, however, in most cases not substantial enough to justify their use. Economic considerations may therefore favour the use of tithonia or FYM when applied alone at 20 kg P ha-1 than when combined with any of the inorganic P sources used in this study at a total P rate of 60 kg ha-1 .
Experimental Agriculture, 2013
SUMMARYSoil acidity and phosphorus (P) deficiency are some of the major causes of low maize yield... more SUMMARYSoil acidity and phosphorus (P) deficiency are some of the major causes of low maize yields in Kenya. This study determined the immediate and residual effects of lime and P fertilizer on soil pH, exchangeable aluminium (Al), available P, maize grain yield, agronomic P use and P fertilizer recovery efficiencies on a western Kenya acid soil. The treatments were: P fertilizer (0, 26 and 52 kg P ha−1 as triple super phosphate) and lime (0, 2, 4 and 6 tons lime ha−1) applied once at the beginning of the study. A burnt liming material with 92.5% calcium carbonate equivalent was used. Soil samples were analysed prior to and after treatment application. The site had low soil pH–H2O (4.9), available P (2.3 mg kg−1), total N (0.17%), high Al (2.0 cmol kg−1 exchangeable Al and 29% Al saturation). Lime reduced soil pH and exchangeable Al, leading to increased soil available P. Lime at 2, 4 and 6 tons ha−1 maintained soil pH ≥ 5.5 for 2, 3 and 4 years, respectively. The study observed tha...
American Journal of Experimental Agriculture, 2014
African Journal of Agricultural Research
Many soils in Western Kenya are acidic and deficient in nitrogen and phosphorus. Acidity hinders ... more Many soils in Western Kenya are acidic and deficient in nitrogen and phosphorus. Acidity hinders crop responses to fertilizers applied to remedy nutrient deficiencies. The common liming materials used to ameliorate acidity are Calcium Oxide (CaO) and Calcium Carbonate (CaCO 3) in powdery formulations. Broadcasting these materials by hand followed by incorporation is recommended on smallholder farms to enhance their effectiveness but this is laborious. Granular lime which is easier to handle was recently introduced but there is little information on its effectiveness. This study therefore tested the effects of CaCO 3 , CaO and granulated lime, applied alone or in combination with fertilizer (Diammonium phosphate (DAP) + calcium ammonium nitrate (CAN)), on maize yield for three seasons, 2015 long rains (LR), 2015 short rains (SR) and 2016 LR at four sites: Butere, Emuhaya, Mumias and Kakamega North in Western Kenya. CaCO 3 and CaO were applied at 2 t ha-1 once in the 2015 LR while granular lime was applied at a ratio of 1:1 with DAP per season. There was no significant effect of lime type on maize yields. Maize did not respond to lime without fertilizer. Application of lime, irrespective of the type, with fertilizer, did not give yields that were significantly different from those of fertilizers alone except at Butere in the 2015 LR when application of CaO and CaCO 3 with fertilizer significantly out yielded those with fertilizer applied alone. Similar results were obtained with granular lime in the 2015 SR at Emuhaya. It was concluded that except for Butere, where maize did not respond to fertilizer alone, the other sites are not sufficiently acid to permit the solubility of Al to toxic levels for maize. More attention should therefore be focused on N and P replenishment at these sites than liming. At Butere, soil acidity is a problem and lime should be applied together with fertilizers.
Archives of Agriculture and Environmental Science
The effect of combining lime and phosphate fertilizer on the performance of soybean (Glycine max ... more The effect of combining lime and phosphate fertilizer on the performance of soybean (Glycine max L.) was investigated in a pot experiment consisting of nine treatments of three rates of lime (0, 4 and 8 t ha−1) in a factorial combination with three rates of phosphorus (0, 15, and 30 kg P ha−1) at Maseno University in western Kenya. There was a significant interaction between the lime and phosphorus rate on the biomass dry weight of soybean. At the rates of 0 and 4 t ha-1 of lime, the biomass dry weight of soybean increased with increasing rates of phosphorus but at 8 t ha-1 of lime, the dry weight of soybean increased from 0 to 15 kg P ha-1 but declined at 30 kg P ha-1. There was however no significant interaction between lime and P rates on grain weight but the effects of both P and lime rate were significant. When applied without lime, 30 kg P ha-1 gave significantly higher grain (5.3 g pot-1) weight than 15 kg P ha-1 (1.6 g pot-1) of soybean, which was also significantly better t...
African Journal of Agricultural Research
Phosphate rock (PR) deposits are the major source of phosphate (P) fertilizers for soil fertility... more Phosphate rock (PR) deposits are the major source of phosphate (P) fertilizers for soil fertility replenishment. The demand for P fertilizers in the year 2014 was 42,706,000 tons and was expected to reach 46,648,000 tons in 2018. Majority of PR deposits are found in only a few countries including Morocco, USA and China. There is however conflicting information on the extent of world PR reserves, therefore, complicating the ability to accurately determine their lifespan. Consequently, proper planning on the utilization of this resource is hampered. Two schools of thought have emerged in regard to the longevity of the PR reserves. Some argue that there is imminent depletion of this resource and the world should therefore be prepared for a looming food crisis. However, based on the most recent estimates of 290 billion tons of PR reserves, some scientists have predicted that the PR reserves will be depleted between the years 2311 and 2411 and therefore conclude that there is no immediate course of alarm. What is not in doubt, however, is the finiteness of PR reserves. Therefore, an approach that encourages society to adopt a sustainable utilization of this phosphate resource should be advocated as an insurance against food insecurity.
Journal of Plant Nutrition
Archives of Agriculture and Environmental Science
The effect of phosphorus (P) rate and crop arrangement on the performance of component crops in m... more The effect of phosphorus (P) rate and crop arrangement on the performance of component crops in maize-bean intercropping systems was investigated at two sites; Malanga and Bugeng’i in western Kenya. A split plot design with five crop arrangements in the main plots i.e., one row of maize alternating with one row of beans (conventional), maize and beans planted in the same hole, two rows of maize alternating with two of beans (Mbili), sole maize and sole beans, in a factorial combination with three P rates; 0, 30, and 60 kg ha-1 in the subplots, was used. Bean yields were low (< 1 t ha-1) but they increased with increasing P rate at both sites. Response of maize to P fertilizer was however poor at Malanga mainly due to Striga weed infestation. Yields of beans did not significantly differ among crop arrangements at both sites. At Bungeng’i, there was a significant interaction between P rate and crop arrangement. At this site, the maize yield in the conventional arrangement increased...
PLOS ONE
Biological nitrogen fixation (BNF) in legumes plays a critical role in improving soil fertility. ... more Biological nitrogen fixation (BNF) in legumes plays a critical role in improving soil fertility. Despite this vital role, there is limited information on the genetic diversity and BNF of bacteria nodulating common bean (Phaseolus vulgaris L.). This study evaluated the genetic diversity and symbiotic nitrogen fixation of bacteria nodulating common bean in soils of Western Kenya. The genetic diversity was determined using 16S rRNA gene partial sequences while BNF was estimated in a greenhouse experiment. The sequences of the native isolates were closely affiliated with members from the genera Pantoea, Klebsiella, Rhizobium, Enterobacter and Bacillus. These results show that apart from rhizobia, there are non-rhizobial strains in the nodules of common bean. The symbiotic efficiency (SE) of native isolates varied and exhibited comparable or superior BNF compared to the local commercial inoculants (CIAT 899 and Strain 446). Isolates (MMUST 003 [KP027691], MMUST 004 [KP027687], MMUST 005 [KP027688], KSM 001 [KP027682], KSM 002 [KP027680], KSM 003 [KP027683] and KSM 005 [KP027685]) recorded equal or significantly higher SE (p < 0.05) compared to N supplemented treatments. The results demonstrate the presence of genetic diversity of native bacteria nodulating bean that are effective in N fixation. These elite bacterial strains should be exploited as candidates for the development of Phaseolus vulgaris inoculants.
Advances in Agriculture
The interactive effects of lime and phosphorus on maize growth in an acid soil were investigated ... more The interactive effects of lime and phosphorus on maize growth in an acid soil were investigated in a greenhouse experiment. A completely randomized design with 12 treatments consisting of four lime levels, 0, 2, 10, and 20 t ha−1, in a factorial combination with three phosphorus rates, 0, 30, and 100 kg ha−1, was used. Maize was grown in pots for six weeks and its heights and dry matter yield were determined and soils were analyzed for available P and exchangeable acidity. Liming significantly reduced the exchangeable acidity in the soils. The effect of lime on available P was not significant but available P increased with increasing P rates. There was a significant effect of lime, P, and P by lime interactions on plant heights and dry matter. Without lime application, dry matter increased with increasing P rates but, with lime, dry mattes increased from 0 to 30 kg P ha−1but declined from 30 to 100 kg P ha−1. The highest dry matter yield (13.8 g pot−1) was obtained with a combined ...
Although the African nightshade is increasingly becoming an important vegetable in Kenya, the con... more Although the African nightshade is increasingly becoming an important vegetable in Kenya, the consumer demand has not been met due to its low yields occasioned by lack of fertilizer use. The general belief is that traditional vegetables are adapted to low fertility. This is despite the fact that phosphorus limits crop production in many parts of western Kenya. The objective of this study was therefore to investigate the effect of phosphorus fertilizer application rate on growth and leaf yields of three types of the African nightshade; Solanum Scabrum (SS), solanum villosum subsp villosum (SVV) and solanum villosum subsp miniatum (SVM). The treatments consisted of four rates of phosphorus (0, 20, 40 and 60 Kg P ha -1) in a factorial combination with three types of the African Nightshade, SS, SVV and SVM. To assess the effect of treatments on plant growth, eight randomly selected plants in each plot were tagged and their heights, number of leaves per plant, leaf area and leaf yields d...
Effects of organic and inorganic materials on soil acidity and phosphorus availability in a soil ... more Effects of organic and inorganic materials on soil acidity and phosphorus availability in a soil incubation study .
Agricultural Reviews
The use of locally available phosphate rock (PR) has often been proposed as a cheaper alternative... more The use of locally available phosphate rock (PR) has often been proposed as a cheaper alternative to the more expensive superphosphate fertilizers to alleviate severe phosphorus deficiencies that threaten food security in East Africa. Extensive research has therefore been conducted in the region over the years focusing on the PR sources, their reactivity, agronomic effectiveness and the economics of their use and adoption. The agronomic effectiveness varied with the type of PR, the site, seasons and crop. Minjingu PR was the most promising among the PRs for direct application but others such as Panda, Sukulu and Busumbu PR were largely ineffective. The financial returns due to use of PR ranged from negative to positive but in many cases were economically not attractive. The adoption of PR use among farmers was dismal with the unavailability of the PR in the market and high cost, paradoxically being cited as the main constraints to its adoption. To enhance the chances of adoption, it...
<p>SDW, N concentration and SE of representative isolates in Kakamega, Kenya.</p
<p>SDW, N concentration and SE of representative isolates in Kisumu, Kenya.</p
Maize production in western Kenya is often limited by deficiencies of nitrogen and phosphorus. We... more Maize production in western Kenya is often limited by deficiencies of nitrogen and phosphorus. We assessed the effectiveness of Tithonia diversifolia green manure (tithonia), farmyard manure (FYM) and urea as sources of nitrogen (N) for maize when inorganic phosphorus (P) fertiliser was either broadcast (BR) or spot-placed in the planting hole (SP) for two consecutive seasons; October to December of 1998 and April to August of 1999 at two sites; Nyabeda and Khwisero in western Kenya. A randomised complete block design with four replications was used. Maize yields were higher at Nyabeda and responded to P application better than at Khwisero. At the same N rate, tithonia and FYM were as effective as urea in increasing maize yields at both sites. There were no significant differences in maize yields when phosphate fertiliser was either BR or SP regardless of the N source used in the first season. However, in the second season, the residual yields for the BR treatments were consistently...
The use of phosphate fertilizers and lime to mitigate P deficiencies and Al toxicities in Kenya h... more The use of phosphate fertilizers and lime to mitigate P deficiencies and Al toxicities in Kenya has not been effective due to their high cost. Organic materials (OMs) are therefore being tested as cheaper alternatives but there are knowledge gaps on how they interact with soil to increase crop yields in acid soils. The effect of two OMs; farmyard manure (FYM) and Tithonia diversifolia (tithonia) green manure, and agricultural lime, each when applied alone or in combination with triple superphosphate (TSP), on selected soil chemical properties related to fertility and nutrient uptake by maize, was tested in a greenhouse experiment. Only the lime and FYM treatments significantly increased the soil pH. Lime was the most effective amendment in reducing the exchangeable Al followed by tithonia and FYM but TSP when applied alone did not reduce exchangeable acidity. The OMs and lime, when applied alone or in combination with TSP reduced the P sorption capacity of the soil but TSP on its ow...
International Journal of Plant & Soil Science, 2015
ABSTRACT The influence of two organic materials (OMs); Tithonia and FYM and inorganic materials; ... more ABSTRACT The influence of two organic materials (OMs); Tithonia and FYM and inorganic materials; triple superphosphate (TSP) and Minjingu phosphate rock (MPR) and Busumbu phosphate rock (BPR), when applied alone or in combination, on P sorption at two sites, Kakamega and Bukura, in western Kenya was investigated. The soil at Bukura was a Ferralsol while that at Kakamega was a Cambisol. A randomized complete block design with 3 replications was used. All the P inputs were uniformly broadcast on the plots and then incorporated into the top soil (0-15 cm) in April 2007. Soils were sampled at 4 and 9 weeks after incorporation of phosphorus inputs (WAI) from each of the treatments and the soil P sorption characteristics determined. The equilibrium P concentration which represents the amount of P in the equilibrium solution at zero P sorbed was < 0.2 mg P L
ISRN Agronomy, 2012
We tested the effects of two organic materials (OMs) of varying chemical characteristics that is,... more We tested the effects of two organic materials (OMs) of varying chemical characteristics that is, farmyard manure (FYM) and Tithonia diversifolia (tithonia), when applied alone or in combination with three inorganic P sources, that is, triple superphosphate (TSP), Minjingu phosphate rock (MPR), and Busumbu phosphate rock (BPR) on soil pH, exchangeable acidity, exchangeable Al, and P availability in an incubation study. FYM and tithonia increased the soil pH and reduced the exchangeable acidity and Al in the short term, but the inorganic P sources did not significantly affect these parameters. The effectiveness of the inorganic P sources in increasing P availability followed the order, TSP > MPR > BPR, while among the OMs, FYM was more effective than tithonia. There was no evidence of synergism in terms of increased available P when organic and inorganic P sources were combined. The combination of OMs with inorganic P fertilizers may, however, have other benefits associated wit...
Nutrient Cycling in Agroecosystems, 2009
Maize production in western Kenya is commonly limited by P deficiencies and aluminum phytotoxicit... more Maize production in western Kenya is commonly limited by P deficiencies and aluminum phytotoxicity. Due to high costs of imported fertilizers and lime, focus is now shifting to solutions that utilize local resources. We tested the effect of three inorganic P sources i.e., triple superphosphate (TSP), Minjingu phosphate rock (MPR) and Busumbu phosphate rock (BPR), each applied in combination with two organic materials (OMs) i.e., farmyard manure (FYM) and Tithonia diversifolia green manure (tithonia), or with urea on soil chemical properties related to soil acidity, P availability and maize yields for three consecutive seasons in western Kenya. The OMs and inorganic P sources were applied to provide 20 and 40 kg P ha-1 respectively in their combination. Where urea was used, the inorganic P sources were applied at 60 kg P ha-1. Maize did not respond to application of TSP, MPR or BPR with urea in the first two seasons. However, after three seasons, maize significantly responded to application of MPR with urea. FYM was more effective than tithonia in increasing the labile inorganic P pools but it gave lower maize yields than tithonia which was more effective in reducing the exchangeable Al. It appears that the ability of an OM to lower the exchangeable Al is more important in increasing maize yields than its ability to increase P availability. The effectiveness of the inorganic P sources in increasing maize yields followed the order of their effectiveness in increasing available P, i.e., TSP [ MPR [ BPR, once Al phytotoxicity was reduced by application of tithonia but the difference between TSP and MPR was not significant. The extra maize yield obtained by the additional 40 kg P ha-1 from the inorganic P sources was, however, in most cases not substantial enough to justify their use. Economic considerations may therefore favour the use of tithonia or FYM when applied alone at 20 kg P ha-1 than when combined with any of the inorganic P sources used in this study at a total P rate of 60 kg ha-1 .
Experimental Agriculture, 2013
SUMMARYSoil acidity and phosphorus (P) deficiency are some of the major causes of low maize yield... more SUMMARYSoil acidity and phosphorus (P) deficiency are some of the major causes of low maize yields in Kenya. This study determined the immediate and residual effects of lime and P fertilizer on soil pH, exchangeable aluminium (Al), available P, maize grain yield, agronomic P use and P fertilizer recovery efficiencies on a western Kenya acid soil. The treatments were: P fertilizer (0, 26 and 52 kg P ha−1 as triple super phosphate) and lime (0, 2, 4 and 6 tons lime ha−1) applied once at the beginning of the study. A burnt liming material with 92.5% calcium carbonate equivalent was used. Soil samples were analysed prior to and after treatment application. The site had low soil pH–H2O (4.9), available P (2.3 mg kg−1), total N (0.17%), high Al (2.0 cmol kg−1 exchangeable Al and 29% Al saturation). Lime reduced soil pH and exchangeable Al, leading to increased soil available P. Lime at 2, 4 and 6 tons ha−1 maintained soil pH ≥ 5.5 for 2, 3 and 4 years, respectively. The study observed tha...
American Journal of Experimental Agriculture, 2014
African Journal of Agricultural Research
Many soils in Western Kenya are acidic and deficient in nitrogen and phosphorus. Acidity hinders ... more Many soils in Western Kenya are acidic and deficient in nitrogen and phosphorus. Acidity hinders crop responses to fertilizers applied to remedy nutrient deficiencies. The common liming materials used to ameliorate acidity are Calcium Oxide (CaO) and Calcium Carbonate (CaCO 3) in powdery formulations. Broadcasting these materials by hand followed by incorporation is recommended on smallholder farms to enhance their effectiveness but this is laborious. Granular lime which is easier to handle was recently introduced but there is little information on its effectiveness. This study therefore tested the effects of CaCO 3 , CaO and granulated lime, applied alone or in combination with fertilizer (Diammonium phosphate (DAP) + calcium ammonium nitrate (CAN)), on maize yield for three seasons, 2015 long rains (LR), 2015 short rains (SR) and 2016 LR at four sites: Butere, Emuhaya, Mumias and Kakamega North in Western Kenya. CaCO 3 and CaO were applied at 2 t ha-1 once in the 2015 LR while granular lime was applied at a ratio of 1:1 with DAP per season. There was no significant effect of lime type on maize yields. Maize did not respond to lime without fertilizer. Application of lime, irrespective of the type, with fertilizer, did not give yields that were significantly different from those of fertilizers alone except at Butere in the 2015 LR when application of CaO and CaCO 3 with fertilizer significantly out yielded those with fertilizer applied alone. Similar results were obtained with granular lime in the 2015 SR at Emuhaya. It was concluded that except for Butere, where maize did not respond to fertilizer alone, the other sites are not sufficiently acid to permit the solubility of Al to toxic levels for maize. More attention should therefore be focused on N and P replenishment at these sites than liming. At Butere, soil acidity is a problem and lime should be applied together with fertilizers.
Archives of Agriculture and Environmental Science
The effect of combining lime and phosphate fertilizer on the performance of soybean (Glycine max ... more The effect of combining lime and phosphate fertilizer on the performance of soybean (Glycine max L.) was investigated in a pot experiment consisting of nine treatments of three rates of lime (0, 4 and 8 t ha−1) in a factorial combination with three rates of phosphorus (0, 15, and 30 kg P ha−1) at Maseno University in western Kenya. There was a significant interaction between the lime and phosphorus rate on the biomass dry weight of soybean. At the rates of 0 and 4 t ha-1 of lime, the biomass dry weight of soybean increased with increasing rates of phosphorus but at 8 t ha-1 of lime, the dry weight of soybean increased from 0 to 15 kg P ha-1 but declined at 30 kg P ha-1. There was however no significant interaction between lime and P rates on grain weight but the effects of both P and lime rate were significant. When applied without lime, 30 kg P ha-1 gave significantly higher grain (5.3 g pot-1) weight than 15 kg P ha-1 (1.6 g pot-1) of soybean, which was also significantly better t...
African Journal of Agricultural Research
Phosphate rock (PR) deposits are the major source of phosphate (P) fertilizers for soil fertility... more Phosphate rock (PR) deposits are the major source of phosphate (P) fertilizers for soil fertility replenishment. The demand for P fertilizers in the year 2014 was 42,706,000 tons and was expected to reach 46,648,000 tons in 2018. Majority of PR deposits are found in only a few countries including Morocco, USA and China. There is however conflicting information on the extent of world PR reserves, therefore, complicating the ability to accurately determine their lifespan. Consequently, proper planning on the utilization of this resource is hampered. Two schools of thought have emerged in regard to the longevity of the PR reserves. Some argue that there is imminent depletion of this resource and the world should therefore be prepared for a looming food crisis. However, based on the most recent estimates of 290 billion tons of PR reserves, some scientists have predicted that the PR reserves will be depleted between the years 2311 and 2411 and therefore conclude that there is no immediate course of alarm. What is not in doubt, however, is the finiteness of PR reserves. Therefore, an approach that encourages society to adopt a sustainable utilization of this phosphate resource should be advocated as an insurance against food insecurity.
Journal of Plant Nutrition
Archives of Agriculture and Environmental Science
The effect of phosphorus (P) rate and crop arrangement on the performance of component crops in m... more The effect of phosphorus (P) rate and crop arrangement on the performance of component crops in maize-bean intercropping systems was investigated at two sites; Malanga and Bugeng’i in western Kenya. A split plot design with five crop arrangements in the main plots i.e., one row of maize alternating with one row of beans (conventional), maize and beans planted in the same hole, two rows of maize alternating with two of beans (Mbili), sole maize and sole beans, in a factorial combination with three P rates; 0, 30, and 60 kg ha-1 in the subplots, was used. Bean yields were low (< 1 t ha-1) but they increased with increasing P rate at both sites. Response of maize to P fertilizer was however poor at Malanga mainly due to Striga weed infestation. Yields of beans did not significantly differ among crop arrangements at both sites. At Bungeng’i, there was a significant interaction between P rate and crop arrangement. At this site, the maize yield in the conventional arrangement increased...
PLOS ONE
Biological nitrogen fixation (BNF) in legumes plays a critical role in improving soil fertility. ... more Biological nitrogen fixation (BNF) in legumes plays a critical role in improving soil fertility. Despite this vital role, there is limited information on the genetic diversity and BNF of bacteria nodulating common bean (Phaseolus vulgaris L.). This study evaluated the genetic diversity and symbiotic nitrogen fixation of bacteria nodulating common bean in soils of Western Kenya. The genetic diversity was determined using 16S rRNA gene partial sequences while BNF was estimated in a greenhouse experiment. The sequences of the native isolates were closely affiliated with members from the genera Pantoea, Klebsiella, Rhizobium, Enterobacter and Bacillus. These results show that apart from rhizobia, there are non-rhizobial strains in the nodules of common bean. The symbiotic efficiency (SE) of native isolates varied and exhibited comparable or superior BNF compared to the local commercial inoculants (CIAT 899 and Strain 446). Isolates (MMUST 003 [KP027691], MMUST 004 [KP027687], MMUST 005 [KP027688], KSM 001 [KP027682], KSM 002 [KP027680], KSM 003 [KP027683] and KSM 005 [KP027685]) recorded equal or significantly higher SE (p < 0.05) compared to N supplemented treatments. The results demonstrate the presence of genetic diversity of native bacteria nodulating bean that are effective in N fixation. These elite bacterial strains should be exploited as candidates for the development of Phaseolus vulgaris inoculants.
Advances in Agriculture
The interactive effects of lime and phosphorus on maize growth in an acid soil were investigated ... more The interactive effects of lime and phosphorus on maize growth in an acid soil were investigated in a greenhouse experiment. A completely randomized design with 12 treatments consisting of four lime levels, 0, 2, 10, and 20 t ha−1, in a factorial combination with three phosphorus rates, 0, 30, and 100 kg ha−1, was used. Maize was grown in pots for six weeks and its heights and dry matter yield were determined and soils were analyzed for available P and exchangeable acidity. Liming significantly reduced the exchangeable acidity in the soils. The effect of lime on available P was not significant but available P increased with increasing P rates. There was a significant effect of lime, P, and P by lime interactions on plant heights and dry matter. Without lime application, dry matter increased with increasing P rates but, with lime, dry mattes increased from 0 to 30 kg P ha−1but declined from 30 to 100 kg P ha−1. The highest dry matter yield (13.8 g pot−1) was obtained with a combined ...
Although the African nightshade is increasingly becoming an important vegetable in Kenya, the con... more Although the African nightshade is increasingly becoming an important vegetable in Kenya, the consumer demand has not been met due to its low yields occasioned by lack of fertilizer use. The general belief is that traditional vegetables are adapted to low fertility. This is despite the fact that phosphorus limits crop production in many parts of western Kenya. The objective of this study was therefore to investigate the effect of phosphorus fertilizer application rate on growth and leaf yields of three types of the African nightshade; Solanum Scabrum (SS), solanum villosum subsp villosum (SVV) and solanum villosum subsp miniatum (SVM). The treatments consisted of four rates of phosphorus (0, 20, 40 and 60 Kg P ha -1) in a factorial combination with three types of the African Nightshade, SS, SVV and SVM. To assess the effect of treatments on plant growth, eight randomly selected plants in each plot were tagged and their heights, number of leaves per plant, leaf area and leaf yields d...
Effects of organic and inorganic materials on soil acidity and phosphorus availability in a soil ... more Effects of organic and inorganic materials on soil acidity and phosphorus availability in a soil incubation study .