Rainfed agriculture: unlocking the potential

Rainfed farming / Soil degradation / Crop production / Climate change / Irrigation methods / Water harvesting / Yield gap / Models / Supplemental irrigation / Water productivity / Watershed management / India

Assessment of strip tillage systems for maize production in semi-arid Ethiopia: effects on grain yield and water balance

International audienceThe traditional tillage implement, the Maresha plow, and the tillage systems that require repeated and cross plowing have caused poor rainfall partitioning, land degradation and hence low water productivity in Ethiopia. Conservation tillage could alleviate these problems. However, no-till can not be feasible for smallholder farmers in semi-arid regions of Ethiopia because of difficulties in maintaining soil cover due to low rainfall and communal grazing and because of high costs of herbicides. Strip tillage systems may offer a solution. This study was initiated to test strip tillage systems using implements that were modified forms of the Maresha plow, and to evaluate the impacts of the new tillage systems on water balance and grain yields of maize (Zea mays XX). Experiments were conducted in two dry semi arid areas called Melkawoba and Wulinchity, in the central Rift Valley of Ethiopia during 2003?2005. Strip tillage systems that involved cultivating planting lines at a spacing of 0.75 m using the Maresha plow followed by subsoiling along the same lines (STS) and without subsoiling (ST) were compared with the traditional tillage system of 3 to 4 times plowing with the Maresha plow (CONV). Soil moisture was monitored to a depth of 1.8 m using Time Domain Reflectometer while surface runoff was measured using rectangular trough installed at the bottom of each plot. STS resulted in the least surface runoff (Qs=17 mm-season?1), the highest transpiration (T=196 mm-season?1), the highest grain yields (Y=2130 kg-ha?1) and the highest water productivity using total evaporation (WPET=0.67 kg-m?3) followed by ST (Qs=25 mm-season?1, T=178 mm-season?1, Y=1840 kg-ha?1, WPET=0.60 kg-m?3) and CONV (Qs=40 mm-season?1,T=158 mm-season?1, Y=1720 kg-ha?1, WPET=0.58 kg-m?3). However, when the time between the last tillage operation and planting of maize was more than 26 days, the reverse occurred. There was no statistically significant change in soil physical and chemical properties after three years of experimenting with different tillage systems

The Limits to Sustainability Science: Ecological Constraints or Endless Innovation?

Ecological principles must govern sustainability, yet sustainability science is largely concerned with social-environmental interactions and barely considers physical limits on resource use. Whether it is possible to overcome such limits can be contested, but the issues raised by a macroecological perspective should be a fundamental part of the United Nations Conference on Sustainable Development (Rio+20)

Integrated Watershed Management in Rainfed Agriculture

This book provides a comprehensive presentation of the realization of improved rainfed agriculture yield in semi-arid and dry land areas. The incentive of watershed programs is to increase the return on investment with over 20% for 65% of the projects that are currently underperforming. Besides techniques to improve the livelihood of the many small-scale farmers in developing countries, it includes examples and case studies for further support. The methods discussed have recently shown to be successful and economically remunerative in India and in various African countries. Intended for professionals (investors, policy makers), researchers and (post) graduate students working on dry land and sustainable agriculture and water and natural resources management. Suited for courses in dry land agriculture, soil and water management and watershed development

Integrating evidence, politics and society: a methodology for the science–policy interface

There is currently intense debate over expertise, evidence and ‘post-truth’ politics, and how this is influencing policy formulation and implementation. In this article, we put forward a methodology for evidence-based policy making intended as a way of helping navigate this web of complexity. Starting from the premise of why it is so crucial that policies to meet major global challenges use scientific evidence, we discuss the socio-political difficulties and complexities that hinder this process. We discuss the necessity of embracing a broader view of what constitutes evidence—science and the evaluation of scientific evidence cannot be divorced from the political, cultural and social debate that inevitably and justifiably surrounds these major issues. As a pre-requisite for effective policy making, we propose a methodology that fully integrates scientific investigation with political debate and social discourse. We describe a rigorous process of mapping, analysis, visualisation and sharing of evidence, constructed from integrating science and social science data. This would then be followed by transparent evidence evaluation, combining independent assessment to test the validity and completeness of the evidence with deliberation to discover how the evidence is perceived, misunderstood or ignored. We outline the opportunities and the problems derived from the use of digital communications, including social media, in this methodology, and emphasise the power of creative and innovative evidence visualisation and sharing in shaping policy

Sustainable Management of Scarce Water Resources in Tropical Rainfed Agriculture

Ensuring global food security for the ever-growing population that will cross 9 billion by 2050 and reducing poverty are challenging tasks. Growing per capita income in the emerging giant economies such as Brazil, Russia, India, and China (BRIe) implies increased additional pressure on global food production due to changing food habits. The increased food production has to come from the available and limited water and land resources, which are finite. The quantity of n~ither available water nor land has increased since 1950, but the availability of water and land per dapita has declined significantly due to increase in global human population. For example, in India, per capita water availability has decreased from 5177 m3 in 1951to 1820 m3 in 2001 due to increase in population from 361 million in 1951 to 1.02 billion in 20m, which is expected to rise to 1.39 billion by 2025 and 1.64 billion by 2050 with associated decrease in per capita water availability of 1341 m' by 2025 and 1140 m' by 2050. respectively.

Managing water in rainfed agriculture

Faczng the food and poverty crzses zn developzng countnes wzll requzre a new emphaszs on smallscale water management zn raznJed agrzculture znvolvzng the redzrectzon of water poltey and large new mvestments Ramfed systems dommate world food production, but water mvestments m ramfed agrIculture have been neglected over the past 50 years Upgradmg ramfed agrIculture promises large SOCIal, economiC, and enVIronmental paybacks, particularly m poverty reduction and economic development Ramfed farmmg covers most of the world's cropland (80%) and produces most of the world's cereal grams (more than 60%), generatmg lIvelIhoods m rural areas and producmg food for cltles EStImates suggest that about 25% of the mcreased water reqUIrement needed to attam the 2015 hunger reduction target of the MillennIUm Development Goal can be contrIbuted from IrrIgation The remammg 75% will have to come from water mvestments m ramfed agnculture.........

The Added Value of Water Footprint Assessment for National Water Policy: A Case Study for Morocco

A Water Footprint Assessment is carried out for Morocco, mapping the water footprint of different activities at river basin and monthly scale, distinguishing between surface- and groundwater. The paper aims to demonstrate the added value of detailed analysis of the human water footprint within a country and thorough assessment of the virtual water flows leaving and entering a country for formulating national water policy. Green, blue and grey water footprint estimates and virtual water flows are mainly derived from a previous grid-based (5×5 arc minute) global study for the period 1996–2005. These estimates are placed in the context of monthly natural runoff and waste assimilation capacity per river basin derived from Moroccan data sources. The study finds that: (i) evaporation from storage reservoirs is the second largest form of blue water consumption in Morocco, after irrigated crop production; (ii) Morocco’s water and land resources are mainly used to produce relatively low-value (in US$/m3 and US$/ha) crops such as cereals, olives and almonds; (iii) most of the virtual water export from Morocco relates to the export of products with a relatively low economic water productivity (in US$/m3); (iv) blue water scarcity on a monthly scale is severe in all river basins and pressure on groundwater resources by abstractions and nitrate pollution is considerable in most basins; (v) the estimated potential water savings by partial relocation of crops to basins where they consume less water and by reducing water footprints of crops down to benchmark levels are significant compared to demand reducing and supply increasing measures considered in Morocco’s national water strateg

Scientific Case for Avoiding Dangerous Climate Change to Protect Young People and Nature

28 pages, 6 figures; version submitted to Proceedings of the National Academy of SciencesGlobal warming due to human-made gases, mainly CO2, is already 0.8{\deg}C and deleterious climate impacts are growing worldwide. More warming is 'in the pipeline' because Earth is out of energy balance, with absorbed solar energy exceeding planetary heat radiation. Maintaining a climate that resembles the Holocene, the world of stable shorelines in which civilization developed, requires rapidly reducing fossil fuel CO2 emissions. Such a scenario is economically sensible and has multiple benefits for humanity and other species. Yet fossil fuel extraction is expanding, including highly carbon-intensive sources that can push the climate system beyond tipping points such that amplifying feedbacks drive further climate change that is practically out of humanity's control. This situation raises profound moral issues as young people, future generations, and nature, with no possibility of protecting their future well-being, will bear the principal consequences of actions and inactions of today's adults

Scientific case for avoiding dangerous climate change to protect young people and nature

28 pages, 6 figures; version submitted to Proceedings of the National Academy of SciencesPeer reviewe