Whole-farm nitrogen cycling and intensification of crop-livestock systems in the highlands of Madagascar: An application of network analysis
Alvarez, S. ; Rufino, M.C. ; Vayssières, J. ; Salgado, P. ; Tittonell, P.A. ; Tillard, E. ; Bocquier, F. - \ 2014
Agricultural Systems 126 (2014). - ISSN 0308-521X - p. 25 - 37.
soil fertility management - nutrient balances - exploring diversity - efficiencies - resource - manure - flows - kenya - conservation - agriculture
Food insecurity, soil fertility depletion and strong competition for biomass are commonly observed in smallholder crop-livestock systems. The objective of this study was to explore options to improve farm-level nitrogen cycling, productivity and economic performance through the analysis of N flows within four contrasting crop-livestock farm systems of Madagascar highlands. Farms were conceptualized as networks where the compartments were the household and their farming activities, all connected by N flows. Indicators assessing network size and cycling, and the organization and diversity of the N flows, were compared with system productivity, food self-sufficiency, and gross margins for the current situation and under four scenarios of intensification (i) dairy production increased by increasing N inputs as supplementary feed; (ii) crop production increased by increasing N inputs as mineral fertilizer; (iii) manure management improved to increase N conservation during storage and application to soils; (iv) a combination of the two most economically attractive scenarios (i and iii). The four case study farms represent local diversity differing widely in terms of network size, with total annual system N throughput ranging from 113 to 1037kgN per capita, and in terms of N cycling, from 3 to 41kgN per capita per year. They differed less in terms of external dependence, from 0.26 to 0.41kgN kgN-1. Improving N conservation through improved manure management (scenario iii) had a positive impact on gross margin, and this in combination with increased concentrate supply (scenario iv) led to increases in whole-farm N use efficiencies from 2% to 50%, in N cycling from 9% to 68% and in food self-sufficiency from 12% to 37% across farm types. Gross margin was the most sensitive indicator to changes in management. Intensification through scenario iv had the highest impact on farm productivity, gross margin, food self-sufficiency, and environment sustainability (N use efficiency, capacity of the soil to stock N)
Farmers' Perceptions of Land Degradation and their Investments in Land Management: a Case Study in the Cental Rift Valley of Ethiopia
Adimassu, Zenebe ; Kessler, A. ; Yirga, C. - \ 2013
Environmental Management 51 (2013)5. - ISSN 0364-152X - p. 989 - 998.
soil fertility management - conservation practices - nutrient balances - tenure security - south wello - highlands - adoption - smallholders - erosion - area
To combat land degradation in the Central Rift Valley (CRV) of Ethiopia, farmers are of crucial importance. If farmers perceive land degradation as a problem, the chance that they invest in land management measures will be enhanced. This study presents farmers’ perceptions of land degradation and their investments in land management, and to what extent the latter are influenced by these perceptions. Water erosion and fertility depletion are taken as main indicators of land degradation, and the results show that farmers perceive an increase in both indicators over the last decade. They are aware of it and consider it as a problem. Nevertheless, farmers’ investments to control water erosion and soil fertility depletion are very limited in the CRV. Results also show that farmers’ awareness of both water erosion and soil fertility decline as a problem is not significantly associated with their investments in land management. Hence, even farmers who perceive land degradation on their fields and are concerned about its increase over the last decade do not significantly invest more in water erosion and soil fertility control measures than farmers who do not perceive these phenomena. Further research is needed to assess which other factors might influence farmers’ investments in land management, especially factors related to socioeconomic characteristics of farm households and plot characteristics which were not addressed by this study.
Farm, Land, and Soil nitrogen budgets for Agriculture in Europe calculated with CAPRI
Leip, A. ; Britz, W. ; Weiss, F. ; Vries, W. de - \ 2011
Environmental Pollution 159 (2011)11. - ISSN 0269-7491 - p. 3243 - 3253.
dairy farms - nutrient balances - production systems - indicators - management - losses - netherlands - efficiency - surpluses - sweden
We calculated farm, land, and soil N-budgets for countries in Europe and the EU27 as a whole using the agro-economic model CAPRI. For EU27, N-surplus is 55 kg N ha-1 yr-1 in a soil budget and 65 kg N2O–N ha-1 yr-1 and 67 kg N ha-1 yr-1 in land and farm budgets, respectively. NUE is 31% for the farm budget, 60% for the land budget and 63% for the soil budget. NS values are mainly related to the excretion (farm budget) and application (soil and land budget) of manure per hectare of total agricultural land. On the other hand, NUE is best explained by the specialization of the agricultural system toward animal production (farm NUE) or the share of imported feedstuff (soil NUE). Total N input, intensive farming, and the specialization to animal production are found to be the main drivers for a high NS and low NUE.
Drivers of land use change and household determinants of sustainability in smallholder farming systems of Eastern Uganda
Ebanyat, P. ; Ridder, N. de; Jager, A. de; Delve, R.J. ; Bekunda, M. ; Giller, K.E. - \ 2010
Population and Environment 31 (2010)6. - ISSN 0199-0039 - p. 474 - 506.
soil fertility management - sub-saharan africa - cover change - nutrient balances - brazilian amazon - level evidence - southern mali - use patterns - dynamics - agriculture
Smallholder farming systems in sub-Saharan Africa have undergone changes in land use, productivity and sustainability. Understanding of the drivers that have led to changes in land use in these systems and factors that influence the systems’ sustainability is useful to guide appropriate targeting of intervention strategies for improvement. We studied low input Teso farming systems in eastern Uganda from 1960 to 2001 in a place-based analysis combined with a comparative analysis of similar low input systems in southern Mali. This study showed that policy-institutional factors next to population growth have driven land use changes in the Teso systems, and that nutrient balances of farm households are useful indicators to identify their sustainability. During the period of analysis, the fraction of land under cultivation increased from 46 to 78%, and communal grazing lands nearly completely disappeared. Cropping diversified over time; cassava overtook cotton and millet in importance, and rice emerged as an alternative cash crop. Impacts of political instability, such as the collapse of cotton marketing and land management institutions, of communal labour arrangements and aggravation of cattle rustling were linked to the changes. Crop productivity in the farming systems is poor and nutrient balances differed between farm types. Balances of N, P and K were all positive for larger farms (LF) that had more cattle and derived a larger proportion of their income from off-farm activities, whereas on the medium farms (MF), small farms with cattle (SF1) and without cattle (SF2) balances were mostly negative. Sustainability of the farming system is driven by livestock, crop production, labour and access to off-farm income. Building private public partnerships around market-oriented crops can be an entry point for encouraging investment in use of external nutrient inputs to boost productivity in such African farming systems. However, intervention strategies should recognise the diversity and heterogeneity between farms to ensure efficient use of these external inputs.
Agricultural carbon sequestration, poverty, and sustainability
Antle, J.M. ; Stoorvogel, J.J. - \ 2008
Environment and Development Economics 13 (2008). - ISSN 1355-770X - p. 327 - 352.
production systems - nutrient balances - soil fertility - kenya - management - africa - design - models
This paper explores the potential impacts of payments for agricultural soil carbon sequestration on poverty of farm households and on the sustainability of agricultural systems, using economic theory combined with evidence from three case studies in Kenya, Peru, and Senegal. The case studies indicate that the likely impact of carbon contracts will be to raise rural incomes and reduce the rate of soil carbon loss. In some cases, carbon contracts may be able to stabilize soil carbon stocks at a higher level than would otherwise be economically feasible. These findings suggest that carbon payments could have a positive impact on the sustainability of production systems while also reducing poverty. The analysis indicates that payments for environmental services are most likely to have a positive impact when they are implemented in an enabling economic and institutional environment.
Ex ante assessment of dual-purpose sweet potato in the crop-livestock system of western Kenya: a minimum-data approach
Claessens, L. ; Stoorvogel, J.J. ; Antle, J.M. - \ 2008
Agricultural Systems 99 (2008)1. - ISSN 0308-521X - p. 13 - 22.
soil fertility management - agricultural production systems - semi-humid tropics - dairy-cows - pennisetum-purpureum - nutrient balances - economic-analysis - farming systems - maize stover - feed
Mixed crop¿livestock systems have a crucial role to play in meeting the agricultural production challenges of smallholder farmers in sub-Saharan Africa. Sweet potato is seen as a potential remedial crop for these farmers because of its high productivity and low input requirements, while its usefulness for both food and feed (dual-purpose) make it attractive in areas where land availability is declining. In this paper, we develop and apply a `minimum-data¿ methodology to assess ex ante the economic viability of adopting dual-purpose sweet potato in Vihiga district, western Kenya. The methodology uses and integrates available socio-economic and bio-physical data on farmers¿ land use allocation, production, and input and output use. Spatially heterogeneous characteristics of the current system regarding resources and productivity are analyzed to assess the profitability of substituting dual-purpose sweet potato for other crops currently grown for food and feed. Results indicate that a substantial number of farmers in the study area could benefit economically from adopting dual-purpose sweet potato. Depending on assumptions made, the adoption rate, expressed as the percentage of the total land under adopting farms, is between 55% and 80%. The analysis shows that the adoption rate is likely to vary positively with the average total yield of dual-purpose sweet potato, the harvest index (the ratio between tuber and fodder yields), the price of milk, and the nutritional value of available fodder. This study demonstrates the usefulness of the minimum-data methodology and provides evidence to support the hypothesis that dissemination of the dual-purpose sweet potato could help improve the livelihoods of smallholder farmers operating in mixed crop¿livestock systems in east Africa.
Heterogeneity of crop productivity and resource use efficiency within smallholder Kenyan farms: Soil fertility gradients or management intensity gradients?
Tittonell, P.A. ; Vanlauwe, B. ; Ridder, N. de; Giller, K.E. - \ 2007
Agricultural Systems 94 (2007)2. - ISSN 0308-521X - p. 376 - 390.
african semiarid tropics - organic-matter - exploring diversity - nutrient balances - savanna - maize - allocation - highlands - dynamics - district
The decrease in crop yields at increasing distances from the homesteads within smallholder farms of Sub-Saharan Africa (SSA) is normally ascribed to the existence of within-farm soil fertility gradients. Field observations also suggest that a large part of such variability is concomitantly caused by poor agronomy. To understand the interaction between soil fertility (S factors) and management decisions (M factors) affecting crop variability, we combined field research conducted in western Kenya (Vihiga, Kakamega and Teso districts; rainfall: 1600, 1800 and 1200 mm, respectively) with explorations using the simple dynamic crop/soil model for dynamic simulation of nutrient balances, previously tested for the region. Field measurements indicated within-farm differences in average maize grain yields of 48% (2.7 vs. 1.4 t ha¿1) in Vihiga and of 60% (1.5 vs. 0.6 t ha¿1) in Teso, between fields that were close and far from the homestead, respectively. Extreme values ranged widely, e.g. between 4.9 and 0.3 t ha¿1 for all the farms surveyed in Vihiga, where the average farm size was 0.6 ha. Maize grain yields tended to increase with increasing contents of soil C, total N, extractable P and exchangeable bases. However, the negative relationship between S factors and distance from the homestead was not as strong as expected, and yield variability was better explained by multiple regression models considering M factors such as planting date, plant density, resource use and weed infestation (40¿60% across sites). Then, we analysed the variation in resource (cash, labour, N) use efficiency within farms of different resource endowments with the aid of the simulation model. N balances at plot scale varied from ca. +20 to ¿18 kg ha¿1, from ¿9 to ¿20 kg ha¿1 and from ¿16 to ¿18 kg ha¿1 for the different fields of the high, medium and low resource endowment case-study farms, respectively. Labour productivities ranged between ca. 10 and 38 kg grain man-day¿1 across field and farm types. The results indicate the need of considering within farm heterogeneity when designing soil fertility management interventions. Resource use efficiency was strongly affected by soil quality. As farmers invest more effort and resources in the more productive and less risky fields, the interaction between S and M factors leads to farmer-driven resource use efficiency gradients within smallholder farms.
Popular myths around soil fertility management in sub-Saharan Africa
Vanlauwe, B. ; Giller, K.E. - \ 2006
Agriculture, Ecosystems and Environment 116 (2006)1-2. - ISSN 0167-8809 - p. 34 - 46.
moist savanna - promiscuous soybeans - nutrient balances - nitrogen-fixation - different scales - organic inputs - maize - benefits - systems - agriculture
The aim of this paper is to demystify some of the popular myths related to tropical soil fertility management that have gained hold in the development community and are often being promulgated by NGO's and development agencies in the tropics. Negative nutrient balances at farm scale or at larger scales are very often presented as proof that soil fertility is at stake in SSA. However, nutrient balances at plot and farm section scale are not always negative. In areas with large nutrient stocks, short-term nutrient mining is fully acceptable. Fertilizer use continues to face considerable controversy in SSA. In this paper, we demonstrate that fertilizers rarely damage the soil; that fertilizers are being used in SSA, often with favourable value-to-cost ratios; and that fertilizers do not cause eutrophication in SSA. Rock phosphates are abundantly present in SSA but most are poorly soluble. Adding these phosphates to compost heaps does not enhance the short-term availability of their R Although organic inputs are essential soil amendments besides fertilizer, organic inputs alone cannot sustain crop production due to limitations in their quality and availability. Organic resources can also potentially stimulate harmful pests and diseases. Legumes are often advocated as important sources of organic matter but not all legumes fix nitrogen, require inoculation, or are a source of free nitrogen, as even green manures require land and labour. Certain grain legumes with high N harvest indices do not improve soil fertility, but remove net amounts of N from the soil. These myths need correction if we are to harness the role of science in the overall goal of assisting farmers to address the acute problems of poor soil fertility for smallholder farmers in SSA.
Assessing soil fertility decline in the tropics using soil chemical data
Hartemink, A.E. - \ 2006
Advances in Agronomy 89 (2006). - ISSN 0065-2113 - p. 179 - 225.
papua-new-guinea - sustainable land management - nutrient balances - organic-matter - sugar-cane - precision agriculture - physical-properties - inorganic nitrogen - brazilian amazon - forest ecosystem
Soil fertility decline is perceived to be widespread in the upland soils of the tropics, particularly in sub-Saharan Africa. Most studies have used nutrient balances to assess the degree and extent of nutrient depletion; these have created awareness but suffer methodological problems as several of the nutrient flows and stocks are not measured. This chapter focuses on the assessment of soil fertility decline using soil chemical data (pH, organic C, total N, available P, cation exchange capacity (CEC), and exchangeable cations) that are routinely collected in soil surveys or for the assessment of fertilizer recommendations. Soil fertility decline can be assessed using a set of properties from different periods at the same site or from different land-use systems with the same soils. The former is easier to interpret; the latter can be rapidly collected but differences may be due to inherent differences and not have resulted from soil management. This study provides an analytical framework for the assessment of soil fertility decline and shows pitfalls and how they should be handled. Boundary conditions are presented that could be used in future studies on soil fertility management and crop productivity in the tropics.
Factors affecting soil quality changes in the North China Plain: a case study of Quzhou County
Chen, J. ; Yu, Z. ; Ouyang, J. ; Mensvoort, M.E.F. van - \ 2006
Agricultural Systems 91 (2006)3. - ISSN 0308-521X - p. 171 - 188.
agricultural land-use - of-the-art - nutrient balances - indicators - management - africa - flows - policies - scales - farm
At the end of the 1970s there were 3,300,000 ha of salt-affected land in the North China Plain. After the successful removal of the salt in the 1980s, the land has gradually been used for increasing intensive forms of agriculture. The Household Responsibility System (HRS) was adopted in Chinese rural areas at the time of the economic reform of the early 1980s. Farm households became the basic decision-making units that could directly control soil quality. This paper describes the change in soil fertility after 20 years of intensive agriculture and the driving factors of soil fertility change. Quzhou County was selected as it is representative for the North China Plain. The soil fertility status and nutrient flows of the salt-affected land for 1980¿1981 and 1999 in Quzhou County were evaluated. Over 20 years, the total nitrogen (N), the extractable phosphorus (P) and the soil organic matter (SOM) in salt-affected land increased by 127%, 601% and 51% respectively; but exchangeable potassium decreased by 31%. The N, P, K and SOM balance in 1980¿1981 was ¿15, ¿2, ¿29 and ¿24 kg ha¿1 y¿1, but in 1999 the N and P balance had changed to 24 kg ha¿1 y¿1 and 25 kg ha¿1 y¿1 as a result of the widespread use of N and P fertilizer. With the rapid increase in crop production and the sparse use of K fertilizer, the K balance continues to be negative. Straw production increased along with crop yields and there was a development of stock breeding. Together with better straw restitution practices, the SOM balance increased to a positive 613 kg ha¿1 y¿1. The analysis of farm household land-use and inputs indicated that there were significant differences in behaviour between almost totally off-farm households and other household types. These differences were in the choice of land-use type, the use of fertilizers and crop residue management. However, there was no significant relationship between socio-economic factors and fertilizer inputs. Current nutrient management is not optimal. Therefore, it is important to establish a better system for bottom-up knowledge collection and transfer of scientific information to farmers.
Revisiting a 'cure against land hunger': soil fertility management and farming systems dynamics in the West African Sahel
Ridder, N. de; Breman, H. ; Keulen, H. van; Stomph, T.J. - \ 2004
Agricultural Systems 80 (2004)2. - ISSN 0308-521X - p. 109 - 131.
rainfall-runoff dynamics - hortonian overland-flow - term crop response - nutrient balances - continuous cultivation - organic-matter - northern nigeria - different scales - southern mali - nitrogen
It should be borne in mind that as a principle of arable farming, what is taken from the soil should be returned to it in full measure.