Microbial fertilizer from PK rocks on lettuce nutrients and soil attributes in consecutive crops

Wagner Da Silva Oliveira,Teresa Hernández,Thatiana Stamford Arnaud,Newton Pereira Stamford,Emmanuella Vila Nova Da Silva,Carlos Garcia Izquierdo

doi:10.1590/s1678-3921.pab2021.v56.01371

Abstract

Abstract: The objective of this work was to evaluate the effect of a microbial fertilizer, produced from phosphate and potassic rocks and earthworm compost, as an alternative to conventional fertilizers, on lettuce (Lactuca sativa) nutrients and soil attributes. The experiment was conducted in consecutive cycles (30 and 60 days) in a soil from the Lorca region, in the municipality of Murcia, Spain. The fertilization treatments were: conventional fertilizer, 100% of the recommended rate (RR); microbial fertilizer, 50% of the RR (5 Mg ha-1); microbial fertilizer, 100% of the RR (10 Mg ha-1); microbial fertilizer, 150% of the RR (15 Mg ha-1); and control, without N-P2O5-K2O fertilization. The microbial fertilizers applied at 100 and 150% of the RR showed significant and positive effects, as well as the best results for plant characteristics. The microbial fertilizer increased total N and available P and K compared with the conventional fertilizer. A residual effect was observed in the successive cycle. The effectiveness of the microbial fertilizer shows it is a viable alternative to conventional fertilizers, with positive effects on plant productivity and soil attributes.

Highlights

The effects of organic fertilizers on plant production are part of the guidelines for the development of a sustainable agriculture that meets economic, social, and environmental standards (Lal, 2010)
The fertilization treatments were: conventional fertilizer, 100% of the recommended rate (RR); microbial fertilizer, 50% of the RR (5 Mg ha-1); microbial fertilizer, 100% of the RR (10 Mg ha-1); microbial fertilizer, 150% of the RR (15 Mg ha-1); and control, without the application of the N-P2O5K2O fertilizer in the second cycle, since the aim was to evaluate the residual effects of the fertilization treatments
This is explained by the slow mineralization of organic matter, leading to a more gradual absorption of N by the plants, which allows the action of metabolic processes and the production of organic structures, reducing nitrate accumulation in the plant shoot (Hernández et al, 2016)

Summary

Introduction

The effects of organic fertilizers on plant production are part of the guidelines for the development of a sustainable agriculture that meets economic, social, and environmental standards (Lal, 2010). Depending on the applied fertilizer, soil conditions and, agriculture may be negatively affected by organic matter loses, nutrient depletion, soil erosion, and groundwater contamination (Montemurro et al, 2015). Recently, in order to enhance nutrient availability in the soil, microorganisms have been added to rocks (Meena et al, 2015; Stamford et al, 2016; Satyaprakash et al, 2017), especially the Acidithiobacillus thiooxidans (Waksman & Joffe 1922) Kelly & Wood 2000 oxidative bacteria, important in nutrient recycling in the soil and in releasing elements contained in rocks (Stamford et al, 2015). To produce an effective microbial fertilizer inoculated with Acidithiobacillus, for example, the inclusion of organic matter is necessary to neutralize the acidity caused by sulfuric acid production (Oliveira et al, 2015). To improve nitrogen content, the addition of free-living diazotrophic bacteria, such as Beijerinckia indica (Starkey & De 1939) Derx 1950, is important due to their effectiveness in enriching N by the biological nitrogen fixation process, as reported by Lima et al (2010)

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Methods

Results