Bio

Dr.Marenya Paswel Phiri

Dr Marenya is a Lecturer at the Department of Agricultural Economics.  He obtained his PhD from Cornell University in 2005 and MSc from the University of Nairobi in 2001.  His obtained a BSc (First Class Honors) in Agriculture from the University of Nairobi in 1995.  Dr Marenya is currently on sabbatical leave at the International Food Policy Research Institute (IFPRI).

Publications


Submitted

Nkonya, E, Xiong W, Deustua J, Kato E.  Submitted.  Why do many smallholder farmers fail to adopt improved land management practices which can improve yields and incomes? The reason is not always because these practices are uneconomical but sometimes it is because resource poverty prevents farmers from tak AbstractWebsite

Why do many smallholder farmers fail to adopt improved land management practices which can improve yields and incomes? The reason is not always because these practices are uneconomical but sometimes it is because resource poverty prevents farmers from taking advantage of yield and income enhancing agricultural practices. In this study we examine the relative merits of using a carbon payment scheme compared to a subsidy policy to help reduce the cost of specific land management practices with productivity and ecosystem benefits such as carbon sequestration. Using a 30-year crop simulation model, we examine the impacts of different soil fertility management treatments (SFTs) on yields and soil carbon and proceed to compute discounted incremental revenue streams over the same period. We find that the SFTs simulated are on average profitable given the conditions assumed in our DSSAT simulations. When carbon was priced at $8 or $12/t CO2e, the increase in incremental incomes generated from a carbon payment were invariably higher than those imputed from a 50% fertilizer subsidy. When carbon was priced at $4/Co2e, the increase was almost similar and sometimes higher than that from the imputed income transfer from a 50% subsidy. If these indications hold in further research, it could imply that using fertilizer subsidies as the sole mechanism for stimulating adoption of improved soil fertility management practices may unnecessarily forgo other complementary and possibly superior alternatives. Depending on the specific economic equity considerations, we conclude that either of these instruments can be used to help farmers break through resource barriers that prevent them from adopting productivity-enhancing and environmentally beneficial agricultural practices. However, given the fiscal burden on public finances and possible opportunity costs of any substantial subsidy program, it is possible that a carbon payment system can be a reasonable alternative assuming the range of carbon prices used in this study and especially if accompanied by measures to ameliorate the costs of fertilizer to farmers.

2012

Marenya, PP;, Smith VH;, Nkonya EM.  2012.  Subsistence farmer preferences for alternative incentive policies to encourage the adoption of conservation agriculture in Malawi: A choice elicitation approach. Abstract

Land degradation in most sub Saharan Africa is a widely recognized problem and is due in large part to poor land management practices. To address this problem, several policy-based incentives to increase the adoption of better land management practices have been proposed, including fertilizer subsidies, cash payments and, more recently, subsidized or commercially offered weather index-based insurance contracts. However, little is known about farmers’ preferences among these policy alternatives, their relative effectiveness, and their likely fiscal implications. Using survey and choice elicitation data from 271 farmers in Central Malawi, this study examines smallholder farmers’ preferences among four major policy options that provide incentives for adopting agroforestry based conservation practices. Our results suggest that even when the expected value of an ideal insurance contract which has no basis risk was 25 percent higher than the cash payment option, sixty percent of the sample preferred the cash payment. Further, the empirical results indicated that cash flow or liquidity constraints may limit farmers’ willingness to use crop insurance as a risk management tool. We conclude that the potential scope for increasing the use of improved land management techniques through fertilizer subsidies, or cash or insurance incentives payments may be substantial, although fertilizer subsidies and cash payments may be less costly approaches than subsidizing insurance contracts.

2011

Nkonya, E; Jawoo, K; MLP; R.  2011.  Land under pressure.. Abstract

This chapter presents and discusses the causes of land degradation, and ways of sustainable land development and agricultural productivity. The evidence presented here suggests several avenues for achieving a world without land degradation. First, efforts to promote sustainable land management need to improve locally and nationally. Second, instead of focusing solely on fertilizer subsidies, countries should use broader and more cost-effective incentives to encourage farmers to adopt integrated soil fertility management.

2009

Marenya, PP;, Barnett CB.  2009.  The effect of soil quality on fertilizer use rates among smallholder farmers in western Kenya. Abstract

Studies of fertilizer use in sub-Saharan Africa have been dominated by analyses of economic and market factors having to do with infrastructure, institutions, and incentives that prevent or foster increased fertilizer demand, largely ignoring how soil fertility status conditions farmer demand for fertilizer. We apply a switching regression model to data from 260 farm households in western Kenya in order to allow for the possibility of discontinuities in fertilizer demand based on a soil carbon content (SCC) threshold. We find that the usual factors reflecting liquidity and quasi-fixed inputs are important on high-SCC plots but not on those with poorer soils. External inputs become less effective on soils with low SCC, hence the discernible shift in behaviors across soil quality regimes. For many farmers, improved fertilizer market conditions alone may be insufficient to stimulate increased fertilizer use without complementary improvements in the biophysical conditions that affect conditional factor demand. JEL classification: Q12, Q18, Q24

Marenya, P, Barrett CB.  2009.  Soil quality and fertilizer use rates among smallholder farmers in western Kenya. Abstract

Studies of fertilizer use in sub-Saharan Africa have been dominated by analyses of economic and market factors having to do with infrastructure, institutions, and incentives that prevent or foster increased fertilizer demand, largely ignoring how soil fertility status conditions farmer demand for fertilizer. We apply a switching regression model to data from 260 farm households in western Kenya in order to allow for the possibility of discontinuities in fertilizer demand based on a soil carbon content (SCC) threshold. We find that the usual factors reflecting liquidity and quasi-fixed inputs are important on high-SCC plots but not on those with poorer soils. External inputs become less effective on soils with low SCC, hence the discernible shift in behaviors across soil quality regimes. For many farmers, improved fertilizer market conditions alone may be insufficient to stimulate increased fertilizer use without complementary improvements in the biophysical conditions that affect conditional factor demand.

Marenya, P, Barrett P;, B C.  2009.  State-conditional Fertilizer Yield Response on Western Kenyan Farms. Abstract

Fertilizer interventions have attained prominence in rural poverty reduction programs in Africa. Using data from maize plots operated by small farmers in western Kenya, we find a von Liebig-type relationship between soil organic matter (SOM) and maize yield response to nitrogen application. Low SOM commonly limits the yield response to mineral fertilizer application. Although fertilizer is, on average, profitable in our sample, on roughly one-third of the plots degraded soils limit the marginal productivity of fertilizer such that it becomes unprofitable at prevailing prices. Moreover, because poorer farmers most commonly cultivate soils deficient in SOM, fertilizer interventions might be less pro-poor than is widely assumed and may instead reinforce ex ante income inequality.

2008

Marenya, Paswel; Barrett, CGTB;.  2008.  Farmers’ Perceptions of Soil Fertility and Fertilizer Yield Response in Kenya. Abstract

To develop soil fertility techniques that respond to farmers’ actual concerns, researchers and agricultural development practitioners in developing countries need to identify how farmers in those regions form perceptions on soil quality and crop response to inputs. Using survey and farm soils data collected in 2002 and 2005 from smallholder farmers in western Kenya, we study whether farmers’ subjective perceptions of soil fertility and impacts of fertilizer vary statistically with objective estimates generated by laboratory and statistical procedures. Our results show that farmers’ perceptions of soil fertility on their plots are largely determined by observed crop yields. By contrast, farmers’ perceptions on the impacts of fertilizer on yields vary rather closely with estimated returns to fertilizer application. This suggests that farmers’ perceptions of soil fertility and the impacts of fertilizer are driven by observed yields. Implications for fertilizer use (the focus of current soil fertility management policies) and long term and integrated soil fertility management are drawn.

2007

2006

Riha, SJ;, Blume LE;, Barret CB;, Kinyangi JM;, Lehmann CJ;, Marenya PP;, Mbugua DM;, Nicholson CF;, Ngoze SO;, Parsons D;, Verchot LV;, Pell AN.  2006.  Long-Term Human and Biophysical Dynamics of Soil Degradation in the Kenyan Highlands.. Abstract

Agroecosystems are among the most tightly coupled of human and natural systems, as farmers make conscious decisions regarding land use and improvement, cropping systems, livestock management and labor allocation. These decisions can profoundly impact the natural resource base, which can then lead to changes in farmers' behaviors. The focus of this study is to understand the long term human and biophysical dynamics of soil degradation. We are especially interested in the role that soil degradation plays in creating poverty traps and in interventions that will strongly impact the dynamics of these systems. We have developed an integrated economic and biophysical systems dynamic model to understand and predict the long term behavior of farms in the Kenyan highlands. Additionally, we have established a chronosequence in western Kenya of farms converted from primary forest to agriculture 100, 70, 50, 30, 15, 5, and < 3 years ago. This chronosequence includes three blocks that contain all time conversions, with 3 farms per conversion. Soil chemistry and soil organic matter fractions have been measured from fields that have never received fertilizer additions. An extensive set of fertility experiments to examine the response of maize to amendment with nitrogen and phosphorus fertilizers, manure and green manure have been established on these soils. Socioeconomic data for these farms has been collected. The chronosequence data is being used to both parameterize and evaluate the model. Preliminary findings indicate that both soil organic matter and maize yields decline after conversion from primary forest, but not at the same rates. As the soil degrades and maize yields decrease, farms become more diversified by shifting some land into perennials. This change in land use is associated with a stable, though decreased, soil fertility level. The relationship of these changes in cropping systems and soil fertility to off farm activities and income will be discussed, as well as the implications of these dynamics for preventing soil degradation and restoring fertility.

Karugia, JT;, Oluoch-Kosura W;, Nyikal R;, Odumbe M;, Marenya PP.  2006.  Access to Land, Income Diversification and Poverty Reduction in Rural Kenya. Abstract

The increasing land scarcity and the worsening trend of poverty in Kenya in recent years have raised concerns about the focus on land-based agriculture as the basis of growth in the rural areas. This paper combines two complementary data sets obtained from two locations in Kenya, drawn against distinctively different land availability patterns, to examine the diverse rural asset base and key sources of livelihood in the rural areas. The analysis reveals that while access to productive land is still an important determinant of livelihoods in the rural areas, even where land holdings are very small, growth in farm productivity alone may not guarantee households sufficient incomes to escape poverty. We find evidence to suggest that growth of non-farm sector is necessary and may be much more important in reducing risks and vulnerability to poverty and should be equally emphasized if households in such regions are to escape poverty. Off-farm earnings accounted for at least 50 percent of total household incomes in the two research locations. The study further revealed existence of significant barriers to entry to remunerative livelihoods both at farm and off-farm level. The study advocates for expansion of educational services, infrastructure and strengthening of rural institutions to spur broad-based development in the rural areas.

Wangila, J, Rasambainarivo J, Randrianarisoa JC, Place F, Oluoch-Kosura, Murithi F, Minten B, Mcpeak J, Marenya PP, Barretta CB.  2006.  Welfare dynamics in rural Kenya and Madagascar.

2005

Barrett, Christopher B; Marenya, PP; MPJ; MF; O-KW; PF; WJ.  2005.  Poverty Dynamics In Rural Kenya.

2004

Otieno, DJ;, Oluoch-Kosura W;, Marenya PP.  2004.  Shaping the Future of African Agriculture for Development: The Role of Social Scientists. Abstract

Food security remains a key challenge to the development efforts of most poor nations. This study investigated the significance of gender (denoted by number of male, female and children in a household) and social amenities in the food security equation. Frequency of food-related illnesses in a household was used as proxy for food security situation, while the entitlement/food utilization side of the equation was represented by the number of male and female children in the household, main source of domestic water, distance to nearest health center, means of transport accessible, household sanitation and level of awareness on basic food preparation and handling methods. Both descriptive and econometric models were used for analysis of primary data from a random sample of 100 farm-households in Yala division, Siaya district of Kenya. This study was conducted in February 2004. Results of this study indicated that majority (74%) of the rural households were experiencing poor food utilization, and were thus generally food insecure. The study also revealed that gender and social amenities were significant in the food security equation. Specifically, there was high correlation between food-related illnesses and use of untapped water, more male children than females in a household, long distance to health centers, lack of quick means of transport, unsafe food disposal and poor food storage habits. In order to improve the food utilization and thereby security for the rural farm-households, the study recommends improvement in the provision of social amenities for both male and female household members equitably.

Kosura-Oluoch, Willis; Marenya PP;, Place F;, Barrett CB.  2004.  Indices and Manifestations of Poverty: Informing anti-poverty Policy Choices. Abstract

Kenya has entered the 21st century with over 50% of its population classified as absolutely poor in that they live on less than a dollar a day. Per capita income is lower than at the end of the 1960’s. Income, assets, and access to essential services are unequally distributed. The country has made important economic reforms, improving macroeconomic management, liberalizing markets and trade, and widening the scope for private sector activity in the hope of improving economic growth and welfare for Kenyans. Yet, despite these reforms the country has experienced little growth and poverty continues to afflict an ever-larger segment of its citizenry, especially in rural areas. Recent debate on the reasons for limited impact of economic reforms on poverty reduction has been of a “top-down’ nature, where analysts consider a policy reform as an external shock and ask how its benefits and costs work their way through the economy to the poor. Increasingly, researchers are recognizing that macroeconomic and sectoral issues are only part of the basis for growth and poverty reduction. What is missing is a “bottom-up” perspective, which starts from the capabilities of individuals, households, and communities. What are their productivities, their environment and how do economic and social developments play out on the ground and how can these developments be influenced? Poverty is a complex, multifaceted concept reflecting a low level of well-being (World Bank 2000). The human well being itself is a multidimensional continuum from extreme deprivation (poverty) to a high attainment or experience of standard of living. 2 In economics use is commonly made of income or expenditure flows as proxies for welfare. This approach is appropriately contested within the social sciences, since well being is experiential, value laden, context and situation dependent and reflects social and personal factors. Poverty is therefore more than lack of material needs, since material sufficiency alone does not guarantee well being. While measurement of poverty is a critical empirical and policy concern, an important phenomenon that has gained currency in recent work on poverty analysis is that of poverty dynamics and poverty traps: who climbs above it, descends below it or oscillates around it – because poverty dynamics is the more fundamental policy concern. Identifying the right policy mix to help a given poor subpopulation depend on an accurate understanding of rural poverty dynamics

Barret, Christopher B; Pell, A; MD; VL; BLGJ; KJ; LE; J.  2004.  The Interplay Between Smallholder Farmers and Fragile Tropical Agroecosystems in the Kenyan Highlands. Abstract

That farmers rely on the land for their livelihoods is obvious. The converse, that ecosystem services depend on farmers' behaviors, must also be recognized if agricultural productivity is to be improved. In sub Saharan Africa, the 70% of the population employed in the agricultural sector (Sanchez 2002) is engaged in an on-going 'dialogue' with the agricultural natural resource base. Recently, this conversation has not been going well: per capita food production has remained stagnant for the last 40 years so now 180 million on the continent lack adequate food, a number that has increased by 100% since 1970 (Sanchez 2002). To provide adequate diets to the African population, increases in crop yields of 3.0 to 3.5% y-1 are needed (Reardon et al. 2001), but such increases have not been realized as average maize yields have remained static at 1200 kg ha-1.

2003

Marenya, Paswel Phiri; Barrett, CB, Oluoch-Kosura W;, Place F;, Barrett CB.  2003.  Education, Nonfarm Income, And Farm Investment In Land-scarce Western Kenya.

2001

PHIRI, MRMARENYAPASWEL.  2001.  The factors Influencing the Adoption and Economics of Crop Management technologies . 5th African Crop Science Society International Conference in Lagos Nigeria October 21-26 2001. : East African Medical Journal Abstract
Presented here is a 16-year-old girl who was referred on 30th January 1996 with diagnosis of cord compression with spastic paraplegia with sensory level at T7/T8. CT scan myelogam confirmed soft tissue density mass displacing cord to the left with no dye being seen beyond T3. Thoracic spine decompressive laminectomy was performed on 1st January 1996 at Nairobi West Hospital extending from T3 to T6 level, which revealed a fibrous haemorrhagic tumour. Histology showed meningioma (mixed fibrous type and meningoepitheliomatous type) with many psammoma bodies. She had a stormy post-operative period, with infection and wound dehiscence. This was treated with appropriate antibiotics and wound care. She was eventually rehabilitated and was able to walk with the aid of a walking frame because of persistent spasticity of right leg. She was seen once as an outpatient by author on 6th July 1996, she was able to use the walking frame, but the right leg was still held in flexion deformity at the knee. She was thus referred to an orthopaedic surgeon for possible tenotomy. She was able to resume her studies at the University ambulating using a wheel chair and walking frame. She presented with worsening of symptoms in 2001 (five years after her first surgery). MRI scan thoracic spine revealed a left anterolateral intradural lesion extending from T3 to T5 vertebral body level compressing and displacing the spinal cord. She had a repeat surgery on 6th March 2001 at Kenyatta National Hospital; spastic paraparesis and urinary incontinenece persisted. She also developed bed sores and recurrent urinary tract infections. She was followed up by the author and other medical personnel in Mwea Mission Hospital where she eventually succumbed in 2005, nine years after her first surgery. This case is presented as a case of incompletely excised spinal meningioma to highlight some of the problems of managing spinal meningiomas when operating microscope and embolisation of tumours are not readily available. Also the family experienced financial constraint in bringing the patient for regular follow-up, and getting access to appropriate antibiotics, catheters and urine bags.

2000

PHIRI, MRMARENYAPASWEL.  2000.  MSc. Thesis study entitled: The Socio Economic Factors Affecting the Adoption of Crop Management Technologies among Smallholder maize Farmers . 5th African Crop Science Society International Conference in Lagos Nigeria October 21-26 2001. : East African Medical Journal Abstract
Presented here is a 16-year-old girl who was referred on 30th January 1996 with diagnosis of cord compression with spastic paraplegia with sensory level at T7/T8. CT scan myelogam confirmed soft tissue density mass displacing cord to the left with no dye being seen beyond T3. Thoracic spine decompressive laminectomy was performed on 1st January 1996 at Nairobi West Hospital extending from T3 to T6 level, which revealed a fibrous haemorrhagic tumour. Histology showed meningioma (mixed fibrous type and meningoepitheliomatous type) with many psammoma bodies. She had a stormy post-operative period, with infection and wound dehiscence. This was treated with appropriate antibiotics and wound care. She was eventually rehabilitated and was able to walk with the aid of a walking frame because of persistent spasticity of right leg. She was seen once as an outpatient by author on 6th July 1996, she was able to use the walking frame, but the right leg was still held in flexion deformity at the knee. She was thus referred to an orthopaedic surgeon for possible tenotomy. She was able to resume her studies at the University ambulating using a wheel chair and walking frame. She presented with worsening of symptoms in 2001 (five years after her first surgery). MRI scan thoracic spine revealed a left anterolateral intradural lesion extending from T3 to T5 vertebral body level compressing and displacing the spinal cord. She had a repeat surgery on 6th March 2001 at Kenyatta National Hospital; spastic paraparesis and urinary incontinenece persisted. She also developed bed sores and recurrent urinary tract infections. She was followed up by the author and other medical personnel in Mwea Mission Hospital where she eventually succumbed in 2005, nine years after her first surgery. This case is presented as a case of incompletely excised spinal meningioma to highlight some of the problems of managing spinal meningiomas when operating microscope and embolisation of tumours are not readily available. Also the family experienced financial constraint in bringing the patient for regular follow-up, and getting access to appropriate antibiotics, catheters and urine bags.

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