The effects of a novel, slow-release application method for an Ascophyllum nodosum seaweed extract biofertilizer on maize (Zea mays L.) growth and nutrient accumulation

Abstract

Applications of Ascophyllum nodosum seaweed extracts (ANE) in a liquid formulation improves yield in some crops by increasing nutrient uptake. However, the repeated applications of liquid formulations needed to induce these effects can be expensive and time-consuming. A one-time application of a slow-release ANE formulation may be a more efficient application method. In the current study, slow-release ANE formulations were developed, and it was hypothesized that applications of these formulations would result in greater growth in maize (Zea mays L.) than the liquid formulation. The twelve slow-release formulations were created by combining ANE and two organic compounds in differing ratios. These formulations were molded into small spheres, with one to three of these “capsules” positioned above the maize kernels at planting. After 10 weeks within a greenhouse (October-December 2018), shoot fresh/dry weight and root dry weight of all plants, as well as nutrient concentrations of shoots/roots from selected treatments were collected. Plant height was also collected halfway through and at the end of this 10-week period. Data from slow-release treatments was compared to controls of liquid ANE, no additives, and a 50/50 composite of the two organic compounds without ANE. Analysis of variance and mean separation tests revealed that certain formulations (i.e. formulation C) and lower application rates of the slow-release biofertilizer resulted in increases in shoot dry weight of up to 47% compared to the liquid seaweed extract control. The data also indicated that higher application rates and higher concentrations of the ANE resulted in decreases in shoot dry weight of up to 33% compared to the liquid seaweed extract control. Maize with the greatest dry weights had significantly lower nutrient concentrations when compared to maize with the lowest dry weights, suggesting that increasing physiological nitrogen use efficiency could have been the potential mode of action for enhancing growth.