Performance Evaluation of a Cascade Cropping System

Abstract

Minimum environmental impact and improved resource efficiency is attainable for soilless cascade systems where the nutrient solution drained from a primary (donor) crop is reused to fertigate a secondary (receiver) crop. However, it is not clear whether the nutrient solution drained from the primary crop can completely satisfy the needs of a secondary crop and if the productivity of the secondary crop is compromised. To test this hypothesis, a prototype soilless cascade system was developed and evaluated. To assess the performance of the system in terms of yield, water and nutrient productivity, a tomato crop was used as the primary crop, while lettuce, spinach and parsley were tested as secondary crops under different drainage management strategies. Measurements of plant growth, crop fresh and dry matter production, leaf chlorophyll and nutrient content, and photosynthesis rate were performed in the secondary crops. In addition, the water productivity and nutrient use efficiency for the fertigation of the primary and secondary crops were recorded. The results showed that the yield of the cascade spinach crop increased by up to 14% compared to the control treatment (monoculture of secondary crop fertigated by standard nutrient solution). The yield of the lettuce and parsley crop was not affected by the reuse of the tomato crop drainage solution. The water productivities of the lettuce, spinach and parsley plants fertigated with pure drainage solution were 50%, 30% and 14% higher than in the control treatment, respectively. The nitrogen and phosphorus use efficiency was improved by more than 50% compared to the control treatments.

Water Nutrient Management in Soilless Plant Cultivation versus Sustainability

“…Cascade systems involve the discharge of the nutrient medium from the primary crop, having high requirements regarding the medium composition to the secondary crop and exhibiting greater tolerance to changes in the nutrient medium composition (Figure 4) [60]. This cropping system is the least widespread [21].…”

“…This cropping system is the least widespread [21]. The cascade management of the nutrient medium allows for savings in the consumption of water and minerals [29,60]. An example of the cascade management of DW was presented by Karatsivou et al (2023) who used tomato as a primary crop, and then lettuce, spinach, and parsley as secondary crops [60].…”

“…The cascade management of the nutrient medium allows for savings in the consumption of water and minerals [29,60]. An example of the cascade management of DW was presented by Karatsivou et al (2023) who used tomato as a primary crop, and then lettuce, spinach, and parsley as secondary crops [60]. The efficiency of nitrogen and phosphorus consumption increased by more than 50%, spinach yield increased by 14% compared to standard nutrient-medium-fed crops, whereas the efficiency of water consumption per lettuce, spinach, and parsley biomass growth was 50%, 30%, and 14% higher, respectively, compared to the standard nutrient medium.…”

Phosphorus Removal Rate and Efficiency in an Electrochemical Sequencing Reactor for the Treatment of Wastewater with Low Organic Carbon Content

“…The concentrations of nutrients in wastewater, such as nitrate reaching up to 614 mg N/L and total phosphorus up to 370 mg P/L, pose a serious threat to both aquatic and groundwater environments [1][2][3]. On the other hand, this represents a case of wasting biogenic substances that could potentially be reused for fertilizing specific types of crops [4][5][6].…”

“…Additionally, the scope of the study included the quantitative (3) and qualitative (4) analysis of the generated sludge. The impact of the applied electric current density on the nitrogen concentration (5) and organic compounds (6) in treated wastewater was also assessed. The obtained results may be utilized in the future to design two-stage systems for wastewater treatment with low organic compound content, targeting the removal of phosphorus and nitrogen.…”