Lettuce talk about sustainable horticulture!
The escalating issue of horticultural waste disposal presents a significant environmental and resource management challenge. In particular, tomato plant residues, a byproduct of greenhouse tomato production, represent a substantial source of untapped nutrients and organic matter. Traditional disposal methods contribute to waste accumulation and environmental burden, highlighting the need for sustainable alternatives. The Biosystems Engineering Group (Uwe Schmidt) and the Urban Plant Ecophysiology Group (Christian Ulrichs) investigated the potential of composting tomato plant residues as a viable fertilizer and soil amendment for lettuce cultivation. Harnessing the natural decomposition process to transform waste into a nutrient-rich substrate could allow closing nutrient cycles and reducing reliance on conventional fertilizers. Check out their Scientia Horticulturae Article!
Abstract
Objective
Resource waste and an environmental burden are consequences of improper disposal of horticultural waste, making it a significant concern in horticulture. Tomato plant residues that accumulate from tomato production in greenhouses, contain a lot of nutrients and organic matter. In the composting process, microorganisms decompose residues into nutrient rich substrates. If these were amended to arable land, this could save fertilizer and help to close nutrient cycles.
Methods
In the present study, it was investigated in a pot experiment whether compost from tomato residues is suitable as fertilizer and soil amendment to produce lettuce (Lactuca sativa 'Speedway'). Therefore, conventional organic fertilizer was substituted either by 100 % or 50 %. In addition, control treatments, with or without conventional organic fertilizer were cultivated.
Results
The results show that the addition of tomato plant compost increases water holding capacity, carbon content, pH, total amount of macro nutrients as well as available P, K and Mg, but reduces ammonium and nitrate content compared to the fertilized control. The 100 % substitute leads to reduced yield and water use efficiency. Therefore, using composted tomato plant residues as a sole N fertilizer is not efficient due to limited plant available N release. Yet, substituting 50 % of conventional organic fertilizer with composted tomato plant residues maintains yields while preserving the aforementioned positive effects.
Conclusion
We demonstrated that composted tomato plant residues are suitable as fertilizer and soil amendment. The residues from one hectare of tomato production have the potential to substitute 50 % of conventional fertilizer for lettuce production on one and the same hectare. This could effectively reduce waste, close nutrition cycles, and promote environmentally friendly horticulture.