Azolla Compost as an Approach for Enhancing Growth, Productivity and Nutrient Uptake of Oryza sativa L.

Mahmoud F Seleiman,Omnia M Elshayb,Lina Baz,Abdelwahed M Nada,Sara A El-Leithy,Ayman H A Mahdi,Bushra A Alhammad

doi:10.3390/agronomy12020416

Abstract

The excessive application of synthetic fertilizers can result in severe environmental risks, while composting green and fresh feedstocks can provide slow-release nutrients. Therefore, the aim of the current investigation was to study the effects of eight individual and combination treatments of azolla compost and NPK synthetic fertilizers (control = no fertilizer and compost; 100% NPK = full recommended dose of synthetic fertilizers as follows: 165 kg N ha−1, 37 kg P2O5 ha−1 and 50 kg K2O ha−1; 70% NPK; 40% NPK; 100% azolla compost (5 t DM ha−1); 50% NPK + 50% azolla compost; 70% NPK + 30% azolla compost and 40% NPK + 60% azolla compost) on rice growth, productivity and nutrient uptake in semi-arid agro-ecosystems. The results indicated that the combination of 40% NPK + 60% azolla compost or 50% NPK + 50% azolla compost resulted in the most optimal growth and the highest yield components. In addition, the application of 40% NPK + 60% azolla compost exhibited similar rice grain yields (10.76 t ha−1) as well as N, P, and K content and uptake compared with the full recommended dose of NPK fertilizer (100% NPK). This study declared that the utilization of azolla compost as an individual or combination application can reduce usage of synthetic fertilizers by up to 60% without significant reduction in the growth and grain productivity of rice.

Highlights

Introduction iationsRice (Oryza sativa L.) is considered the second most important cereal crop that is being used as food source for 50% of the world population due to its nourishment [1].The world’s rice cultivated area was about 164.19 M ha with a total annual grains production of 756.74 Mt and 4.60 t grains per ha in 2018 [2]
The main observation indicated that treatment of 50% NPK + 50% azolla compost resulted in the highest chlorophyll content in terms of SPAD values (44.22 and 45.61), leaf area index (LAI)
For the LAI and dry matter production (DMP) variables, the influence of incorporated azolla compost with synthetic fertilizer may have reinforced the availability of macro and micronutrients

Summary

Introduction

Rice (Oryza sativa L.) is considered the second most important cereal crop (after wheat) that is being used as food source for 50% of the world population due to its nourishment [1]. The world’s rice cultivated area was about 164.19 M ha with a total annual grains production of 756.74 Mt and 4.60 t grains per ha in 2018 [2]. In order to cultivate such large areas, millions of tons of synthetic fertilizers are needed to produce high grain yields for rapidly growing populations and their food requirements [3,4]. In 2018–2019 about 188 Mt was the aggregate world consumption of fertilizers, at a cost of about 155.8 billion dollars; this is expected to grow annually by 3.8% until 2024 [6]. The incremental application of synthetic fertilizers can cause harmful impacts on soil organic matter that can result in N deficiency [4], and enhance salt accumulation in soil [5].

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