Introduction: food crops in a changing climate

Changes in both the mean and the variability of climate, whether naturally forced, or due to human activities, pose a threat to crop production globally. This paper summarizes discussions of this issue at a meeting of the Royal Society in April 2005. Recent advances in understanding the sensitivity of crops to weather, climate and the levels of particular gases in the atmosphere indicate that the impact of these factors on crop yields and quality may be more severe than previously thought. There is increasing information on the importance to crop yields of extremes of temperature and rainfall at key stages of crop development. Agriculture will itself impact on the climate system and a greater understanding of these feedbacks is needed. Complex models are required to perform simulations of climate variability and change, together with predictions of how crops will respond to different climate variables. Variability of climate, such as that associated with El Niño events, has large impacts on crop production. If skilful predictions of the probability of such events occurring can be made a season or more in advance, then agricultural and other societal responses can be made. The development of strategies to adapt to variations in the current climate may also build resilience to changes in future climate. Africa will be the part of the world that is most vulnerable to climate variability and change, but knowledge of how to use climate information and the regional impacts of climate variability and change in Africa is rudimentary. In order to develop appropriate adaptation strategies globally, predictions about changes in the quantity and quality of food crops need to be considered in the context of the entire food chain from production to distribution, access and utilization. Recommendations for future research priorities are given.

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Crop responses to climatic variation

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2005.1752 ◽

2005 ◽

Vol 360 (1463) ◽

pp. 2021-2035 ◽

Cited By ~ 535

Author(s):

John R Porter ◽

Mikhail A Semenov

Keyword(s):

Climate Change ◽

Climate Variability ◽

Crop Production ◽

Experimental Studies ◽

Well Being ◽

Stress Factors ◽

Food Crops ◽

Temperature And Precipitation ◽

Threshold Temperatures ◽

The Impact

The yield and quality of food crops is central to the well being of humans and is directly affected by climate and weather. Initial studies of climate change on crops focussed on effects of increased carbon dioxide (CO 2 ) level and/or global mean temperature and/or rainfall and nutrition on crop production. However, crops can respond nonlinearly to changes in their growing conditions, exhibit threshold responses and are subject to combinations of stress factors that affect their growth, development and yield. Thus, climate variability and changes in the frequency of extreme events are important for yield, its stability and quality. In this context, threshold temperatures for crop processes are found not to differ greatly for different crops and are important to define for the major food crops, to assist climate modellers predict the occurrence of crop critical temperatures and their temporal resolution. This paper demonstrates the impacts of climate variability for crop production in a number of crops. Increasing temperature and precipitation variability increases the risks to yield, as shown via computer simulation and experimental studies. The issue of food quality has not been given sufficient importance when assessing the impact of climate change for food and this is addressed. Using simulation models of wheat, the concentration of grain protein is shown to respond to changes in the mean and variability of temperature and precipitation events. The paper concludes with discussion of adaptation possibilities for crops in response to drought and argues that characters that enable better exploration of the soil and slower leaf canopy expansion could lead to crop higher transpiration efficiency.

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Climate Variability Since 1970 and Farmers’ Observations in Northern Ghana

Sustainable Agriculture Research ◽

10.5539/sar.v5n2p41 ◽

2016 ◽

Vol 5 (2) ◽

pp. 41 ◽

Cited By ~ 5

Author(s):

Emmanuel Nyadzi

Keyword(s):

Climate Change ◽

Climate Variability ◽

Water Conservation ◽

Crop Production ◽

Meteorological Data ◽

Northern Region ◽

Northern Ghana ◽

Climate Variability And Change ◽

Urban Centers ◽

Access To Credit

<p>The study examines how farmers’ observations of climate variability and change correspond with 42 years (1970-2011) meteorological data of temperature and rainfall. It shows how farmers in the Northern Region of Ghana adjust to the changing climate and explore the various obstacles that hinder the implementation of their adaptation strategies. With the help of an extension officer, 200 farmers from 20 communities were randomly selected based on their farming records. Temperatures over the last four decades (1970-2009) increased at a rate of 0.04 (± 0.41) ˚C and 0.3(± 0.13)˚C from 2010-2011 which is consistent to the farmers (82.5%) observations. Rainfall within the districts are characterised by inter-annual and monthly variability. It experienced an increased rate of 0.66 (± 8.30) mm from 1970-2009, which was inconsistent with the farmers (81.5%) observation. It however decreased from 2010-2011 at a huge rate of -22.49 (±15.90) mm which probably was the reason majority of the respondents claim rainfall was decreasing. Only 64.5% of the respondents had adjusted their farming activities because of climate variability and change. They apply fertilizers and pesticides, practice soil and water conservation, and irrigation for communities close to dams. Respondents desire to continue their current adaptation methods but may in the future consider changing crop variety, water-harvesting techniques, change crop production to livestock keeping, and possibly migrate to urban centers. Lack of climate change education, low access to credit and agricultural inputs are some militating factors crippling the farmers’ effort to adapt to climate change.</p>

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The Pitfalls of Relating Weeds, Herbicide Use, and Crop Yield: Don't Fall Into the Trap! A Critical Review

Frontiers in Agronomy ◽

10.3389/fagro.2020.615470 ◽

2020 ◽

Vol 2 ◽

Author(s):

Nathalie Colbach ◽

Sandrine Petit ◽

Bruno Chauvel ◽

Violaine Deytieux ◽

Martin Lechenet ◽

...

Keyword(s):

Crop Yield ◽

Weed Management ◽

Crop Production ◽

Yield Loss ◽

Crop Yields ◽

Cropping Systems ◽

Crop Productivity ◽

Arable Farming ◽

Herbicide Use ◽

The Impact

The growing recognition of the environmental and health issues associated to pesticide use requires to investigate how to manage weeds with less or no herbicides in arable farming while maintaining crop productivity. The questions of weed harmfulness, herbicide efficacy, the effects of herbicide use on crop yields, and the effect of reducing herbicides on crop production have been addressed over the years but results and interpretations often appear contradictory. In this paper, we critically analyze studies that have focused on the herbicide use, weeds and crop yield nexus. We identified many inconsistencies in the published results and demonstrate that these often stem from differences in the methodologies used and in the choice of the conceptual model that links the three items. Our main findings are: (1) although our review confirms that herbicide reduction increases weed infestation if not compensated by other cultural techniques, there are many shortcomings in the different methods used to assess the impact of weeds on crop production; (2) Reducing herbicide use rarely results in increased crop yield loss due to weeds if farmers compensate low herbicide use by other efficient cultural practices; (3) There is a need for comprehensive studies describing the effect of cropping systems on crop production that explicitly include weeds and disentangle the impact of herbicides from the effect of other practices on weeds and on crop production. We propose a framework that presents all the links and feed-backs that must be considered when analyzing the herbicide-weed-crop yield nexus. We then provide a number of methodological recommendations for future studies. We conclude that, since weeds are causing yield loss, reduced herbicide use and maintained crop productivity necessarily requires a redesign of cropping systems. These new systems should include both agronomic and biodiversity-based levers acting in concert to deliver sustainable weed management.

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South Africa’s increasing climate variability and its effect on food production

Outlook on Agriculture ◽

10.1177/00307270211004970 ◽

2021 ◽

pp. 003072702110049

Author(s):

Mashudu Tshikovhi ◽

Roscoe Bertrum van Wyk

Keyword(s):

South Africa ◽

Climate Variability ◽

Food Production ◽

Fixed Effects ◽

Crop Yields ◽

Negative Impact ◽

Secondary Data ◽

Mean Annual Temperature ◽

Fixed Effects Panel Regression ◽

The Impact

This study examines the impact of increasing climate variability on food production in South Africa, focusing on maize and wheat yields. A two-way fixed effects panel regression model was used to assess the climate variability impacts, analysing secondary data for the period 2000 to 2019 for nine provinces in South Africa. The study found that increasing climate variability has a negative impact on maize and wheat production in South Africa. Specifically, the results indicated a negative correlation between mean annual temperature with both maize and wheat yields. A decrease in precipitation affected maize yields negatively, while the impact on wheat yields was positive, although insignificant. This analysis, therefore, depicted that crop yields generally increase with more annual precipitation and decrease with higher temperatures. The study recommends that funding initiatives to educate farmers on increasing climate variability and its effects on farming activities in South Africa should be prioritised.

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Quantifying the impact of land degradation on crop production: the case of Senegal

Solid Earth ◽

10.5194/se-7-93-2016 ◽

2016 ◽

Vol 7 (1) ◽

pp. 93-103 ◽

Cited By ~ 8

Author(s):

B. G. J. S. Sonneveld ◽

M. A. Keyzer ◽

D. Ndiaye

Keyword(s):

Land Degradation ◽

Crop Production ◽

Crop Yields ◽

Fertilizer Application ◽

Yield Reduction ◽

Sufficient Information ◽

Persistent Problem ◽

Confounding Variables ◽

A Site ◽

The Impact

Abstract. Land degradation has been a persistent problem in Senegal for more than a century and by now has become a serious impediment to long-term development. In this paper, we quantify the impact of land degradation on crop yields using the results of a nationwide land degradation assessment. For this, the study needs to address two issues. First, the land degradation assessment comprises qualitative expert judgements that have to be converted into more objective, quantitative terms. We propose a land degradation index and assess its plausibility. Second, observational data on soils, land use, and rainfall do not provide sufficient information to isolate the impact of land degradation. We, therefore, design a pseudo-experiment that for sites with otherwise similar circumstances compares the yield of a site with and one without land degradation. This pairing exercise is conducted under a gradual refining of the classification of circumstances, until a more or less stable response to land degradation is obtained. In this way, we hope to have controlled sufficiently for confounding variables that will bias the estimation of the impact of land degradation on crop yields. A small number of shared characteristics reveal tendencies of "severe" land degradation levels being associated with declining yields as compared to similar sites with "low" degradation levels. However, as we zoom in at more detail some exceptions come to the fore, in particular in areas without fertilizer application. Yet, our overall conclusion is that yield reduction is associated with higher levels of land degradation, irrespective of whether fertilizer is being applied or not.

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Climate Variability and Change in Bihar, India: Challenges and Opportunities for Sustainable Crop Production

Sustainability ◽

10.3390/su9111998 ◽

2017 ◽

Vol 9 (11) ◽

pp. 1998 ◽

Cited By ~ 11

Author(s):

Kindie Tesfaye ◽

Pramod Aggarwal ◽

Fasil Mequanint ◽

Paresh Shirsath ◽

Clare Stirling ◽

...

Keyword(s):

Climate Variability ◽

Crop Production ◽

Climate Variability And Change ◽

Sustainable Crop Production ◽

Challenges And Opportunities

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CLIMATE VARIABILITY AND CHANGE: FARMER PERCEPTIONS AND UNDERSTANDING OF INTRA-SEASONAL VARIABILITY IN RAINFALL AND ASSOCIATED RISK IN SEMI-ARID KENYA

Experimental Agriculture ◽

10.1017/s0014479710000918 ◽

2011 ◽

Vol 47 (2) ◽

pp. 267-291 ◽

Cited By ~ 91

Author(s):

K. P. C. RAO ◽

W. G. NDEGWA ◽

K. KIZITO ◽

A. OYOO

Keyword(s):

Climate Variability ◽

Crop Production ◽

Smallholder Farmers ◽

Crop Productivity ◽

General Tendency ◽

Climate Variability And Change ◽

Negative Impacts ◽

Probabilistic Nature ◽

Semi Arid

SUMMARYThis study examines farmers’ perceptions of short- and long-term variability in climate, their ability to discern trends in climate and how the perceived trends converge with actual weather observations in five districts of Eastern Province in Kenya where the climate is semi-arid with high intra- and inter-annual variability in rainfall. Field surveys to elicit farmers’ perceptions about climate variability and change were conducted in Machakos, Makueni, Kitui, Mwingi and Mutomo districts. Long-term rainfall records from five meteorological stations within a 10 km radius from the survey locations were obtained from the Kenya Meteorological Department and were analysed to compare with farmers’ observations. Farmers’ responses indicate that they are well aware of the general climate in their location, its variability, the probabilistic nature of the variability and the impacts of this variability on crop production. However, their ability to synthesize the knowledge they have gained from their observations and discern long-term trends in the probabilistic distribution of seasonal conditions is more subjective, mainly due to the compounding interactions between climate and other factors such as soil fertility, soil water and land use change that determine the climate's overall influence on crop productivity. There is a general tendency among the farmers to give greater weight to negative impacts leading to higher risk perception. In relation to long-term changes in the climate, farmer observations in our study that rainfall patterns are changing corroborated well with reported perceptions from other places across the African continent but were not supported by the observed trends in rainfall data from the five study locations. The main implication of our findings is the need to be aware of and account for the risk during the development and promotion of technologies involving significant investments by smallholder farmers and exercise caution in interpreting farmers’ perceptions about long-term climate variability and change.

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Effects of Research Priorities the Northeast Marketing and Competition Research Planning Steering Committee

Journal of the Northeastern Agricultural Economics Council ◽

10.1017/s0163548400002107 ◽

1978 ◽

Vol 7 (2) ◽

pp. 33-34

Author(s):

Olan D. Forker

Keyword(s):

Research Program ◽

Research Priorities ◽

Steering Committee ◽

Development Stage ◽

Future Research ◽

Allocation Of Resources ◽

Master Program ◽

Research Programs ◽

Research Areas ◽

The Impact

The Research Program Steering Committee on Marketing and Competition was created in 1977 by the Northeast Experiment Station Directors. It was one of ten such committees asked to develop a master research program to identify research areas of high priority, coordinate and consolidate current research programs, implement new approaches, and coordinate future research plans. This particular committee was asked to cover research programs in “Marketing and Competition” (RP 6.03). The Master Program, still in the development stage, is an indicative plan. It is designed to indicate needed areas of research and priorities and suggests a mechanism for encouraging the allocation of resources in the indicated directions. The effect on research priorities will depend on how well we did our job, on how seriously the limited number of involved researchers take our suggestions, and on the impact we all have on the allocation of funds and human resources.

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Improving the Water-Use Efficiency and the Agricultural Productivity: An Application Case in a Modernized Semiarid Region in North-Central Mexico

Sustainability ◽

10.3390/su12198122 ◽

2020 ◽

Vol 12 (19) ◽

pp. 8122

Author(s):

Julián González-Trinidad ◽

Hugo Enrique Júnez-Ferreira ◽

Carlos Bautista-Capetillo ◽

Laura Ávila Dávila ◽

Cruz Octavio Robles Rovelo

Keyword(s):

Crop Yields ◽

Water Productivity ◽

Agricultural Productivity ◽

Free Water ◽

Field Capacity ◽

Semiarid Region ◽

Future Research ◽

Drought Period ◽

Water Volumes ◽

The Impact

The increasing population demands a greater quantity of food. In order to satisfy the world’s demand, one of the main challenges worldwide consists of modernizing the current irrigation systems. This research shows an experience carried out in a modernized irrigation module in Central-North Mexico following these objectives: to evaluate the impact of the modernization of the irrigation module, to analyze the agricultural productivity, and to assess a group of parameters related with the agricultural production (system conduction and distribution efficiencies, water productivity, among others) and the water volumes after and before the modernization. After a drought period, a methodology was performed in commercial parcels in 2013 to increase the yield of different crops. Some of the activities were: soil leveling, estimation of the soil properties (field capacity, wilting point, bulk density, pH, and organic matter), optimum fertilization applications, use of a model to scheduling irrigation, measure volumes extracted at the parcel level. With the modernization and the method used, around 1800 and 2000 m3 ha−1 were saved with respect to the initial granted volume by the Comisión Nacional del Agua and increase in the global efficiency was also achieved (from 55% to 85%). All crop yields increased, i.e., for corn from 2.5 kg/m3 to 3.8 kg/m3. The impact of modernization accompanied with an effective operation allowed a significant increase of the crop yield and water productivity. Despite a controlled distribution of water being carried out, future research should contemplate free water demand scenarios and automation irrigation for improving the module operation.

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