Life cycle impact assessment of seaweed based biostimulant production from onshore cultivated Kappaphycus alvarezii (Doty) Doty ex Silva—Is it environmentally sustainable?

Abstract

Seaweeds are recognized as one of the important sources of plant biostimulants and are now being increasingly used to enhance crop productivity. Kappaphycus alvarezii is one such seaweed whose extract (pristine sap) has been reported to improve the yield and quality of several crops. In order to evaluate whether the sap obtained from this seaweed is environmentally sustainable, life cycle impact assessment was carried out for the production of 1kL of seaweed extract, at factory gate, from the fresh biomass of K. alvarezii grown onshore in open sea conditions. Financial allocation was carried out to account for the production of carrageenan, a downstream product. Impacts were also assessed for different means of transportation necessary for the movement of liquid extract to the regional storage facility. Additionally, eight different scenarios that were hypothesized to effectively reduce the environmental impacts, especially under the category of climate change, were also assessed and compared with base case scenario. Pristine sap extracted from K. alvarezii was found to be environmentally sustainable having a low carbon foot print of 118.6kg CO2 equivalents per kiloliter of its production at factory gate following price allocation. It was observed that rail, road and ship transport modes increased the impacts under the climate change category by 51.8%, 138.5% and 14.1%, respectively, when compared to base case, implying that transport through sea or rail is more environmental friendly. Unexpectedly, increase in net biomass production by 25% from 200kg to 250kg per raft did not have any significant impact on the reduction of carbon foot print at factory gate. The study for the first time enables to quantitatively compare the environmental benefits that can accrue following the use of this biostimulant on various crops, either by way of substitution of mineral fertilizers or by supplementation.