Effect of Various Rates of P from Alternative and Traditional Sources on Butterhead Lettuce (Lactuca sativa L.) Grown on Peat Substrate

Abstract

Previous research indicated the potential use of struvite (STR) as an alternative source of phosphorus (P) in crop production. A greenhouse experiment was conducted to evaluate the effect of STR and triple superphosphate (TSP) on the growth and chemical composition of butterhead lettuce grown on peat substrate over a three-month period (May–July). Both alternative (STR) and conventional (TSP) fertilizers were applied at three rates: (1) recommended rate based on the elemental content of substrate and crop nutritional need; (2) reduced rate (50% lower than recommended); and (3) increased rate (50% higher than recommended). Unfertilized (control) plants were also grown in the pot experiment. As expected, fertilizer application tended to increase the content of heavy metals in the substrate. Thus, an increase in Zn, Pb, and Cu content in peat substrate was found following STR amendments. However, compared with unfertilized plants, the applied rates of the STR and TSP fertilizers did not increase the content of Cd and Cu in the plant leaf, while Hg content was below the detection limit. In addition, Zn content in the plant leaf significantly decreased following STR and TSP applications. In comparison to unfertilized plants, both alternative and conventional fertilizers increased the content of P and nitrate nitrogen (N-NO3−) in the plant leaf while their effect on Mg content was negligible. The increased rate of STR was the best fertilizer treatment because it produced the largest number of leaves, which were also characterized by the highest P content. Our findings showed that STR was an effective source of P in butterhead lettuce cultivation without adverse effects on heavy metal accumulation.

Effect of struvite (Crystal Green) fertilization on soil element content determined by different methods under soybean cultivation

“…In our study, struvite fertilization did not have a more significant effect on seed yield and phosphorus uptake than that seen in other studies 15 , 34 , 35 but it did have an effect on seed phosphorus content. Despite the lack of significant differences, greater values of seed yield and P uptake can be attributed mainly to the greater amount of Mg contained in Crystal Green fertilizer and its synergistic effect on P uptake 36 .…”

“…Struvite also contains some heavy metals, as wastewater contains a significant amount of such elements; however, these occur within acceptable limits, as has been proved in our own research 12 . Experimental data from various plant species proves that struvite fertilization results in similar plant yields to those achieved with mineral fertilization 7 , 8 , 12 – 15 .…”

“…Phosphorus recovery comprised phosphorus minerals precipitation from sewage sludge as struvite (magnesium ammonium phosphate hexahydrate, MgNH 4 PO 4 6H 2 O). Struvite contains N (2%), P (24%) and Mg (10%) and is characterized by a low heavy metal content compared to triple superphosphate 7 , 15 . From the chemical point of view, it is not pure struvite.…”

“…A promising possibility is struvite (MgNH 4 PO 4 6H 2 O), which can be recovered from sewage sludge. Struvite recovery has several additional advantages not only in agriculture sector but also in wastewater treatment plants 4 – 6 , as struvite is regarded as an alternative source of elements such as phosphorus, nitrogen and magnesium for agricultural purposes 7 – 9 . Struvite has a theoretical P content close to that of phosphate rock (12.6% dry weight [DW]) and has been shown to be an effective P fertilizer especially in acidic soils and is considered a slow-release fertilizer that can reduce P losses to the environment 10 , 11 .…”

The effect of struvite fertilization (Crystal Green) on the nutritional value of soybean

“…Most agricultural elds are P-poor and are rapidly depleting P supplies, which is a serious global problem [23][24][25] . Balance disturbance of elements in the soil can change the dynamics of other nutrients in plant parts by affecting their uptake and assimilation 26 .…”