Agricultural by-products, that is primary residue, industrial by-products and animal manure, are an important source of nutrients and carbon for maintaining soil quality and crop production but can also be valorised through treatment pathways such as fermentation, incineration or a combination of these called bio-refinery. Here, we provide an overview of opportunity to reduce environmental impact of valorising agricultural by-products. We estimate the available by-products in Northwestern Europe as a case study and the maximum and realistic greenhouse gas reduction potentials. Availability, collectability, the original use and environmental impact including land use changes, soil carbon sequestration and pollution swapping are discussed as critical factors when valorising agricultural by-products.
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Phosphate is essential for agricultural production and therefore plays a key role in the global production of food and biofuels. There are no agricultural alternatives for phosphate, and a substantial fraction of our annual phosphate consumption is dispersed into the environment where it is largely lost to agriculture. Phosphate is an irreplaceable, and to a considerable extent non-renewable, resource that is being exploited at an ever increasing rate. The ongoing depletion of phosphate resources combined with recently increased phosphate prices urge us to reconsider our phosphate consumption patterns. In addition to economic and geo-political reasons, further reducing phosphate consumption would moreover be beneficial to the quality of our environment. Even if we increase the reserve base, for which there are plenty of opportunities, it is clear that the phosphate industry will sooner or later have to make a switch from a reserve-based industry to a recycling industry
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Ghanaian farmers suffer from a decline in cocoa production partly due to damages and diseases from insect pests. To increase predation by bats on insects on the cocoa plantations we installed two different types of bat boxes on 15 plantations around the village of Buoyem. Bat activity, bat species composition (numbers of insectivorous and frugivorous bats) and insect abundance were measured before and after bat box installation. Insectivorous bats were present on all ofthe sampled plantations, namelyleaf-nosed bats (Hipposideros sp.), slit-faced bats (Nycteridae sp.), horseshoe bats (Rhinolophus sp.) and vesper bats (Vespertilionidae sp.). Furthermore, no correlation between insect abundance and bat activity could be detected. The bat boxes were not occupied yet during the research period since rainy season started in the second half of the measurements and bat activity decreases with increasing precipitation which is supported by our Un dings. Additionally, the available time period between in stallation and measuring of the effects of the boxes was very short when compared to similar researches. Bats alsohave different preferences per species for size and shape of bat boxes and the number of naturally available roosting sites also influences bat box occupancy. Our results suggest that bats are abundant above cocoa plantations in Buoyem and therefore bat boxes have the potential to be ahelpful tool in insect pest control.
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