Reducing N Fertilization without Yield Penalties in Maize with a Commercially Available Seed Dressing

Abstract

Introducing smart and sustainable tools for climate change adaptation and mitigation is a major need to support agriculture’s productivity potential. We assessed the effects of the processed gypsum seed dressing SOP® COCUS MAIZE+ (SCM), combined with a gradient of N fertilization rates (i.e. 0 %, 70 % equal to 160 kg N ha-1, and 100 % equal to 230 kg N ha-1) in maize (Zea mays L.), on: (i) grain yield, (ii) root length density (RLD) and diameter class length (DCL), (iii) biodiversity of soil bacteria and fungi, and (iv) Greenhouse Gases (GHGs, i.e. N2O, CO2, and CH4) emission. Grain yield increased with SCM by 1 Mg ha-1 (+8 %). The same occurred for overall RLD (+12 %) and DCL of very fine, fine, and medium root classes. At anthesis, soil microbial biodiversity was not affected by treatments, suggesting earlier plant-rhizosphere interactions. Soil GHGs showed that (i) the main driver of N losses as N2O is the N-fertilization level, and (ii) decreasing N-fertilization in maize from 100 % to 70 % decreased N2O emissions by 509 mg N-N2O m-2 y-1. Since maize grain yield under SCM with 70 % N-fertilization was similar to that under Control with 100 % N-fertilization, we concluded that under our experimental conditions SCM may be used for reducing N input (-30 %) and N2O emissions (-23 %), while contemporarily maintaining maize yield. Hence, SCM can be considered an available tool to improve agriculture’s alignment to the United Nation Sustainable Development Goals (UN SDGs) and to comply with Europe’s Farm to Fork strategy for reducing N-fertilizer inputs.

Enhanced Nutritional Quality of Sweet Maize Kernel in Response to Cover Crops and Bio-Fertilizer

“…Rosa [10] has argued that winter turnip rape (Brassicaceae) and white clover (Fabaceae) positively affected the quality of sweet maize kernels by increase of vitamin C concentration and reduction of P concentration, which was partially supported by results achieved in this experiment. Furthermore, increased kernel yield and concentration of glucose, fructose, vitamin C, Mg, Fe, and Zn in the variant with BF proves its importance as sustainable practice [12][13][14].…”

“…Phenolics could also reduce the bio-availability of essential elements [17], so CC with reducing potential of phenolics accumulation in maize kernel, such as fodder kale (T4) and field pea + winter oats (T5) are advantageous. In general, higher values of ratio between phytic acid and essential elements were noticed in BF variant, contributing to the increased availability of essential macro-and micro-elements from poorly accessible forms [13,14,44]. It is important to emphasize that enhanced absorption of essential elements from the maize kernel during digestion could be enhanced by the increased YP concentration [18,19], what was obtained in variants without BF.…”

“…Microorganisms, including bio-fertilizers, have a key role in crop productivity, maintaining soil fertility, stimulating plant growth and productivity, plant defence and stress tolerance, increasing uptake and accumulation of N, P, Fe, Mn, Zn, and Cu in plant tissues, enhancing antioxidants and photosynthetic pigments [12,13]. They are also able to reduce phytic acid concentration (the main anti-nutrient which binds mineral nutrients) in maize grain [14].…”

Reducing Topdressing N Fertilization with Variable Rates Does Not Reduce Maize Yield

“…In the present case study, located in eastern Lombardy (Italy), maize production is experiencing relevant variability, being caused mainly by the low price on the market and pest control regulations and limits, which results in increased imports from countries outside the EU [31]. It was observed that dairy farmers hardly adhere to the organic recommended fertilizer application rates due to the high availability of manure and slurry [28,[32][33][34][35][36]; however, to ensure high crop yields, topdressing mineral N is used despite the purchase and environmental costs [37]. Even considering the current subsidized rates, mineral fertilizers still represent a substantial budget item in European farms [38].…”

“…The proximal sensing equipment is typically used to manage different field homogeneous zones, also known as management zones. They represent subfield regions with the same soil traits and hydrologic characteristics within which a single strategy (e.g., fertilization rate) is appropriate [26][27][28]. Since it is now possible to map the maize yields and moisture level at harvest with very high spatial resolution, the major challenge is modulating the amount of fertilizer equally to match the crop demand [29].…”