Bee abundance and soil nitrogen availability interactively modulate apple quality and quantity in intensive agricultural landscapes of China
Wu, Panlong ; Tscharntke, Teja ; Westphal, Catrin ; Wang, Meina ; Olhnuud, Aruhan ; Xu, Huanli ; Yu, Zhenrong ; Werf, Wopke van der; Liu, Yunhui - \ 2021
Agriculture, Ecosystems and Environment 305 (2021). - ISSN 0167-8809
Ecological intensification - Landscape composition - Pollinator - Robinia forests
Bees provide important pollination services for crops, but pollination limitation is a common problem in agricultural landscapes worldwide. To promote ecological intensification in fruit production, more knowledge is needed concerning the interacting effects of insect pollination services and soil fertility on crop quality and quantity. We investigated the effects of three pollination treatments (open, self and hand pollination) on apple quantity and quality parameters. We also analyzed the effects of bee abundance (wild bees and managed honeybees (Apis mellifera)) and soil nitrogen on fruit quantity and quality, and the responses of bee abundance and species richness to landscape metrics. Apple fruit set and yield of open pollinated flowers increased by 57 % and 25 t/ha (compared to bagged controls), respectively. Hand pollination further enhanced yields by 7 t/ha (compared to open pollination; i.e. to 39 t/ha), indicating pollination limitation in the orchards. Seed number was highest in open pollinated fruits, and increased with bee abundance if soil nitrogen was low, but decreased with bee abundance at high nitrogen levels, possibly due to higher flower density resulting in pollinator dilution effects. Higher seed numbers reduced the proportion of deformed apples and thus increased fruit quality. The percent of surrounding semi-natural habitats positively affected species richness of wild bees in apple orchards. We conclude that yield and quality of apples may benefit from ecological intensification comprising the augmentation of wild bees by semi-natural habitat and lowering of fertilizer inputs.
Pollination contribution to crop yield is often context-dependent: A review of experimental evidence
Tamburini, Giovanni ; Bommarco, Riccardo ; Kleijn, David ; Putten, Wim H. van der; Marini, Lorenzo - \ 2019
Agriculture, Ecosystems and Environment 280 (2019). - ISSN 0167-8809 - p. 16 - 23.
Ecological intensification - Interaction - Pest control - Pollinators - Soil services - Synergies
Insect pollination is a well-studied ecosystem service that supports production in 75% of globally important crops. Although yield is known to be sustained and regulated by a bundle of ecosystem services and management factors, the contribution of pollination to yield has been mostly studied in isolation. Here, we compiled and reviewed research on the contribution of pollination to crop yield under different environmental conditions, where the potential interaction between pollination and other factors contributing to yield, such as nutrient availability and control of pests, was tested. Specifically, we explored whether pollination displayed synergistic, compensatory or additive effects with concomitant factors. The literature search resulted in 24 peer-reviewed studies for a total of 39 individual tests of interactions. Studies examined responses in 13 crops testing interactions both at the local and the landscape scale. Interactions between pollination and other factors influencing yield were observed for several crops and mostly displayed positive-synergistic relationships. Crop life-history traits such as pollination dependency were found to affect the plant response to variations in resource and pollen availability. Soil properties and crop pests might affect contribution of pollination to yield by altering the amount of resources a plant can allocate to reproduction, independently of the amount of pollen provided. Current management strategies to enhance pollinators might fail to increase pollination benefits in landscapes characterized by poor soil resources or ineffective pest control. We propose that our understanding of the effects of crop-pollinator interactions will benefit by focusing on plant traits and physiological responses. Combining knowledge from plant physiology and ecology with technological advances in agriculture is needed to design novel management strategies to maximize pollination benefits and support yields and reduce environmental impacts of food production.
Crop yield gap and stability in organic and conventional farming systems
Schrama, M. ; Haan, J.J. de; Kroonen, M. ; Verstegen, H. ; Putten, W.H. Van der - \ 2018
Agriculture, Ecosystems and Environment 256 (2018). - ISSN 0167-8809 - p. 123 - 130.
Ecological intensification - Nutrient leaching - Soil communities - Spatial stability - Sustainable intensification - Variability
A key challenge for sustainable intensification of agriculture is to produce increasing amounts of food and feed with minimal biodiversity loss, nutrient leaching, and greenhouse gas emissions. Organic farming is considered more sustainable, however, less productive than conventional farming. We analysed results from an experiment started under identical soil conditions comparing one organic and two conventional farming systems. Initially, yields in the organic farming system were lower, but approached those of both conventional systems after 10–13 years, while requiring lower nitrogen inputs. Unexpectedly, organic farming resulted in lower coefficient of variation, indicating enhanced spatial stability, of pH, nutrient mineralization, nutrient availability, and abundance of soil biota. Organic farming also resulted in improved soil structure with higher organic matter concentrations and higher soil aggregation, a profound reduction in groundwater nitrate concentrations, and fewer plant-parasitic nematodes. Temporal stability between the three farming systems was similar, but when excluding years of Phytophthora outbreaks in potato, temporal stability was higher in the organic farming system. There are two non-mutually exclusive mechanistic explanations for these results. First, the enhanced spatial stability in the organic farming system could result from changes in resource-based (i.e. bottom-up) processes, which coincides with the observed higher nutrient provisioning throughout the season in soils with more organic matter. Second, enhanced resource inputs may also affect stability via increased predator-based (i.e. top-down) control. According to this explanation, predators stabilize population dynamics of soil organisms, which is supported by the observed higher soil food web biomass in the organic farming system.We conclude that closure of the yield gap between organic and conventional farming can be a matter of time and that organic farming may result in greater spatial stability of soil biotic and abiotic properties and soil processes. This is likely due to the time required to fundamentally alter soil properties.
Maximizing farm-level uptake and diffusion of biological control innovations in today’s digital era
Wyckhuys, Kris A.G. ; Bentley, Jeff W. ; Lie, Rico ; Nghiem, Le Thi Phuong ; Fredrix, Marjon - \ 2018
BioControl 63 (2018)1. - ISSN 1386-6141 - p. 133 - 148.
Conservation biological control - Crop protection - Ecological intensification - Information diffusion - IPM - Rural sociology - Socio-ecological systems
When anthropologists interviewed Honduran and Nepali smallholders in the mid-1990s, they were told that “Insects are a terrible mistake in God’s creation” and “There’s nothing that kills them, except for insecticides”. Even growers who maintained a close bond with nature were either entirely unaware of natural pest control, or expressed doubt about the actual value of these services on their farm. Farmers’ knowledge, beliefs and attitudes towards pests and natural enemies are of paramount importance to the practice of biological control, but are all too often disregarded. In this study, we conduct a retrospective analysis of the extent to which social science facets have been incorporated into biological control research over the past 25 years. Next, we critically examine various biological control forms, concepts and technologies using a ‘diffusion of innovations’ framework, and identify elements that hamper their diffusion and farm-level uptake. Lastly, we introduce effective observation-based learning strategies, such as farmer field schools to promote biological control, and list how those participatory approaches can be further enriched with information and communication technologies (ICT). Although biological control scientists have made substantial technological progress and generate nearly 1000 papers annually, only a fraction (1.4%) of those address social science or technology transfer aspects. To ease obstacles to enhanced farmer learning about biological control, we describe ways to communicate biological control concepts and technologies for four divergent agricultural knowledge systems (as identified within a matrix built around ‘cultural importance’ and ‘ease of observation’). Furthermore, we describe how biological control innovations suffer a number of notable shortcomings that hamper their farm-level adoption and subsequent diffusion, and point at ways to remediate those by tactical communication campaigns or customized, (ICT-based) adult education programs. Amongst others, we outline how video, smart phones, or tablets can be used to convey key ecological concepts and biocontrol technologies, and facilitate social learning. In today’s digital era, cross-disciplinary science and deliberate multi-stakeholder engagement will provide biocontrol advocates the necessary means to bolster farmer adoption rates, counter-act surging insecticide use, and restore public trust in one of nature’s prime services.