M. Mucheru-Muna

Determinants of the decision to adopt integrated soil fertility management practices by smallholder farmers in the central highlands of Kenya

SUMMARY Declining soil fertility is a major cause of low per capita food production on smallholder farms of sub-Saharan Africa. This study attempted to provide an empirical explanation of the factors associated with farmers’ decisions to adopt or not to adopt newly introduced integrated soil fertility management (ISFM) technologies consisting of combinations of organics and mineral fertilizer in Meru South district of the central highlands of Kenya. Out of 106 households interviewed, 46% were ‘adopters’ while 54% were ‘non-adopters’. A logistic regression model showed that the factors that significantly influenced adoption positively were farm management, ability to hire labour and months in a year households bought food for their families, while age of household head and number of mature cattle negatively influenced adoption. The implication of these results is that the adoption of ISFM practices could be enhanced through targeting of younger families where both spouses work on the farm full-time and food insecure households. It is also important to target farmers that lack access to other sources of soil fertility improvement. Examples include farmers that do not own cattle or those owning few and who, therefore, have limited access to animal manure.

Rainfall Variability, Drought Characterization, and Efficacy of Rainfall Data Reconstruction: Case of Eastern Kenya

This study examined the extent of seasonal rainfall variability, drought occurrence, and the efficacy of interpolation techniques in eastern Kenya. Analyses of rainfall variability utilized rainfall anomaly index, coefficients of variance, and probability analyses. Spline, Kriging, and inverse distance weighting interpolation techniques were assessed using daily rainfall data and digital elevation model using ArcGIS. Validation of these interpolation methods was evaluated by comparing the modelled/generated rainfall values and the observed daily rainfall data using root mean square errors and mean absolute errors statistics. Results showed 90% chance of below cropping threshold rainfall (500 mm) exceeding 258.1 mm during short rains in Embu for one year return period. Rainfall variability was found to be high in seasonal amounts (CV = 0.56, 0.47, and 0.59) and in number of rainy days (CV = 0.88, 0.49, and 0.53) in Machang’a, Kiritiri, and Kindaruma, respectively. Monthly rainfall variability was found to be equally high during April and November (CV = 0.48, 0.49, and 0.76) with high probabilities (0.67) of droughts exceeding 15 days in Machang’a and Kindaruma. Dry-spell probabilities within growing months were high, (91%, 93%, 81%, and 60%) in Kiambere, Kindaruma, Machang’a, and Embu, respectively. Kriging interpolation method emerged as the most appropriate geostatistical interpolation technique suitable for spatial rainfall maps generation for the study region.

ENHANCING MAIZE PRODUCTIVITY AND PROFITABILITY USING ORGANIC INPUTS AND MINERAL FERTILIZER IN CENTRAL KENYA SMALL-HOLD FARMS

SUMMARY Declining land productivity is a major problem facing smallholder farmers today in Sub-Saharan Africa, and as a result increase in maize grain yield has historically staggered behind yield gains that have been achieved elsewhere in the world. This decline primarily results from reduction in soil fertility caused by continuous cultivation without adequate addition of external nutrient inputs. Improved soil fertility management practices, which combine organic and mineral fertilizer inputs, can enable efficient use of inputs applied, and can increase overall system’s productivity. The trials were established at two sites with different soil fertility status to determine the effects of various organic sources (Tithonia diversifolia, Mucuna pruriens, Calliandra calothyrsus and cattle manure) and their combinations with mineral fertilizer on maize grain yield, economic return and soil chemical properties. Drought spells were common during the peak water requirement periods, and during all the seasons most (90%) of the rainfall was received before 50% flowering. In good and poor sites, there was a significant (p < 0.001) effect of season on maize grain yield. Tithonia diversifolia recorded the highest (4.2 t ha −1 ) average maize grain yield in the poor site, while Calliandra calothyrsus gave the highest (4.8 t ha −1 ) average maize grain yield in the good site. Maize grain yields were lower in treatments with sole fertilizer compared with treatments that included organic fertilizers. The maize grain yields were higher with sole organics compared with treatments integrating organic and inorganic fertilizers. Soil pH increment was statistically significant in the sole manure treatment in good and poor sites (t-test, p = 0.036 and 0.013), respectively. In the poor site, magnesium increased significantly in the sole manure and manure + 30 kg N ha−1 treatments with t-test p = 0.006 and 0.027, respectively. Soil potassium was significant in the sole manure treatment (t-test, p = 0.03). Generally the economic returns were low, with negative net benefits and benefit cost ratio of less than 1. Inorganic fertilizer recorded the highest net benefit and return to labour (p < 0.001 and <0.01, respectively) in the good site. The treatments that had very high maize grain yields did not lead to improved soil fertility, thus there is need for tradeoffs between yield gains and soil fertility management when selecting agricultural production technologies.

Improving food production using ‘best bet’ soil fertility technologies in the Central highlands of Kenya

Declining crop productivity is a major challenge facing smallholder farmers in central highlands of Kenya. This decline is caused by continuous cultivation of soils without adequate addition of external inputs in form of manures and fertilizers. With this background, an on-station trial was initiated at Embu in 1992 to evaluate the feasibility of using two leguminous shrubs; Calliandra calothyrsus and Leucaena leucocephala for improving food production. In 2000, an off-station farmers’ participatory trial aimed at offering farmers soil enhancing technologies for replenishing soil fertility was established in Meru South District. The results from the Embu on-station trial indicate that, over the 11 years of study, calliandra and leucaena biomass transfer with half recommended rate of inorganic fertilizer treatments gave the best average maize grain yields of 3.3 Mg ha-1. Treatment where calliandra was alley cropped with maize but the prunings removed recorded the lowest maize yield of 1.2 Mg ha-1. Treatments with calliandra and leucana biomass transfer had similar yields but treatments that were alley cropped with leucaena did better than those that were alley cropped with calliandra. On the other hand, results from the off-station trial in Meru South indicate that, on average, across the seven seasons, sole tithonia gave the highest maize grain yield followed closely by tithonia with half recommended rate of inorganic fertilizer with 6.4 and 6.3 Mg ha-1 respectively. Control gave the lowest yield of 2.2 Mg ha-1 across the seasons. On average, integration of organic an inorganic sources of nutrients gave higher yields compared to all the other treatments.

Using Apsim-Model as a decision-support-tool for long-term integrated-nitrogen-management and maize productivity under semi-arid conditions in Kenya

This study was part of a research conducted through funding from the Regional Universities Forum for Capacity Building in Agriculture (RUFORUM), Call ID RU/CGC/GRG/15/10/109.

Effects of different maize (Zea mays L.) - soybean (Glycine max (L.) Merrill) intercropping patterns on soil mineral-N, N-uptake and soil properties

The adoption of ISFM technologies such as maize-soybean intercropping system is being promoted as one of the options to address low soil fertility and crop productivity among the farmers of the central highland of Kenya. The purpose of this study was therefore to determine the effects of maize-soybean intercropping patterns on soil inorganic N, N uptake and soil chemical properties. The experiment conducted during 2012 LR and 2012 SR and it was arranged in a randomized complete block design (RCBD) with four replications. The treatments were four maize (M) – soybean (S) intercropping patterns (conventional=1M:1S; MBILI-MBILI=2M:2S; 2M:4S; 2M:6S) and two sole crops of maize and soybean, respectively. The results showed that at Embu during 2012 LR, at harvest the MBILI and 2M:4S treatments observed significantly (p=0.0525) the lowest N03

Strategies to Adapt, Disseminate and Scale Out Legume Based Technologies

The full potential of legume based technologies can only be achieved if farmers widely adopt these technologies. Widespread adoption of legume-based technologies calls for the identification of spatial and temporal niches of legumes in the farming systems. The entry point may be immediate provision of food and fodder but also contribution to soil fertility improvement and erosion control among others. Whichever the objective, there is need to demonstrate the immediate benefits to be accrued by the adopters if large scale adoption is to be achieved. There is need to address challenges hindering widescale adoption of legume technologies such as availability of improved germplasm, poor markets and policy. Whereas the national systems play a key role in promoting legumes, the private sector continues to effectively complement government efforts to increase availability and accessibility to quality seed. Flow of knowledge cannot be achieved through a narrow prescriptive approach, but requires development and testing of a battery of possible interventions for soil fertility improvements suited to the specific agroecological environment together with the farmers. Better and innovative mechanisms are required for sharing of knowledge between all those involved in trying to improve the productivity of smallholder agriculture. This should cover the use or both print and audio media as complement to the traditional approaches such as the use of field days and onfarm demonstrations. The focus of this chapter is therefore to look at how the above issues have been addressed in adapting and disseminating legume-based technologies in Africa.

Effect of Organic Inputs and Mineral Fertilizer on Maize Yield in a Ferralsol and a Nitisol Soil in Central Kenya

Declining land productivity is a major problem facing smallholder farmers in Kenya today. This decline primarily results from a reduction in soil fertility caused by continuous cultivation without adequate addition of external nutrient inputs. Improved fertility management combining organic and mineral fertilizer inputs can enable efficient use of the inputs applied and increase overall system’s productivity. Field trials were established at three sites in distinct agro-ecological zones of central Kenya (one site at Machang’a and two sites at Mucwa with different soil fertility status) aiming to determine the effects of various organic sources (tithonia, lantana, mucuna, calliandra and manure) and combinations with mineral N fertilizer on maize grain yield during four consecutive seasons. In Machang’a site, sole manure recorded the highest maize grain yield across the four seasons. In Mucwa poor site, sole tithonia gave the highest maize grain yield during the four seasons, while in Mucwa good site, sole calliandra gave the highest maize grain yields. Generally, the maize grain yields were lower in the treatments with fertilizer alone compared to the treatments with organics across the three sites in the four seasons due to the poorly distributed rainfall. In Machang’a during the SR 2004 and SR 2005 seasons, the treatments with integration of organic and mineral fertilizer inputs were significantly higher than treatment with the sole organics; however, in Mucwa good and poor sites, generally the treatments with sole organics did better than the ones with integration of mineral N fertilizer and organics with the exception of the mucuna treatment which did significantly better in the integration compared to the sole application.

Economic evaluation of local inputs in Meru South District, Kenya

Declining land productivity is a major problem facing smallholder farmers in Kenya today. This decline is as a result of reduced soil fertility caused by continuous cultivation without adequate addition of manures and fertilizers. Low soil fertility is one of the greatest challenges facing farmers in the central highlands of Kenya. A farmers’ participatory trial was established in Meru South District, Kenya in 2000 to investigate feasible soil nutrient replenishment technologies for poor resource smallholder farmers. Results across seven seasons indicate that sole tithonia gave the highest grain yield followed closely by tithonia with half recommended rate of inorganic fertilizer with 6.4 and 6.3 Mg ha-1respectively. The control treatment gave the lowest yield of 2.2 Mg ha-1 across the seasons. The integration of organic and inorganic nutrient sources of N gave higher maize grain yield as compared to the sole organic materials in all seven seasons. Economic analyses indicate that on average tithonia with half the recommended rate of inorganic fertilizer recorded the highest net benefit (US

Climate smart agriculture adaptation strategies for rain-fed agriculture in drought-prone areas of Central Kenya

787.2) whereas the control treatment gave the lowest benefit (US