## 3 Soil Features as a Consequence of Reduced Fertilization
### Soil Chemistry
#### 3.1.6 Strategies for N Efficiency in Reduced Fertilization  
Interestingly, according to [PERSON] et al. [67], a 20% reduction in N fertilization, aligned with the European Union's recommendations, did not result in a decline in the chemical parameters of soils, such as pH; WHC; total C [TC]; total sulfur [TS]; easily degradable carbon [EDC]; the content of N forms [Olsen P]; total concentrations of K, Mg, and Ca; respiration activity [RA]; and amount of humans-like substances [HS], under maize cultivation. This suggests that moderate reductions in N input may not immediately impact soil chemistry, especially for certain crops like maize, which is efficient in nutrient uptake. Nevertheless, the chemical properties of agricultural soils can still be influenced by specific cultivation techniques and the type of crops grown; that is why it is crucial to implement strategies that mitigate the potential negative effects of reduced N fertilization [23]. N-fixing cover crops, like clover and alfalfa, introduce atmospheric nitrogen into the soil through symbiosis with bacteria, reducing the need for synthetic N [68]. When incorporated as green manure, they release N slowly over time as they decompose, ensuring a steady supply of N even when synthetic inputs are reduced [68; 69]. Another complementary approach involves organic amendments, such as compost or manure, which enrich the soil with organic N and increase its OM content. These amendments break down gradually, releasing N and other essential nutrients at a controlled rate, improving nutrient retention and reducing the risk of leaching [53; 70]. N stabilizers and inhibitors can also be applied to enhance the efficiency of the available N [71]. In tandem with improved soil management practices, such as reduced tillage and the enhancement of soil OM, the soil's ability to retain N is further strengthened. Soils with higher OM content and better structure possess greater CEC, which helps retain essential nutrients such as Ca, Mg, and K, thus preventing nutrient depletion even with less N fertilization [53; 72; 73].  
\begin{table}
\begin{tabular}{c c c} \hline
**Bacterial Group** & **Optimal pH Range** & **Activity** \\ \hline N-fixing bacteria & 6.0–8.5 & nitrification (pH below 6.0 stops their activity, which results in NH\({}_{3}\) accumulation in the soil \\ \hline Denitrifying bacteria & 6.0–8.0 & denitrification (at a lower pH, denitrification is inhibited, reducing N losses from the soil) \\ \hline Cellulolytic bacteria & 5.5–7.5 & decomposition of cellulose (lower pH reduces their activity and slows down OM breakdown) \\ \hline Acidophilic bacteria & 3.5–6.5 & predominant in acidic soils \\ \hline Ammonifying bacteria & 6.0–8.0 & ammonification (lower pH reduces their activity, affecting N availability) \\ \hline Proteolytic bacteria & 6.0–8.0 & breaking down proteins and other N compounds (at a lower pH, their abundance and activity decline) \\ \hline Symbiotic & 6.0–7.5 & forming symbiotic relationships with legumumous plants, fixing atmospheric N (lower pH significantly reduces their ability to fix N) \\ \hline \end{tabular}
\end{table}
Table 1: Soil bacterial groups and their functions depending on soil pH based on [PERSON] [36], [PERSON] et al. [64], [PERSON] et al. [65], and [PERSON] et al. [66].  
By incorporating these strategies, it is possible to maintain an optimal balance of N and other nutrients in the soil, mitigating the negative effects of reduced N fertilization while enhancing soil fertility in a sustainable manner. These practices support a stable chemical environment in the soil, preserving its nutrient-holding capacity and ensuring long-term productivity.