Using the reasoned nitrogen (N) fertilization method in potato crops (Solanum tuberosum L.) requires the validation of its parameters under the probable conditions of crop response. A field experiment in an Andisol was established to assess the parameters of this method and the nitrogen utilization efficiency of the crop. To describe the crop N response, five statistical models were used. Dry matter production and nutrient concentration were measured in tubers, leaves, fruits and roots. At both the beginning and the end of the experiment soil samples were collected to evaluate the mineral N. The quadratic-potential model was the most appropriate to describe the positive response of the potato crop to available nitrogen, from an initial level of nitrogen (the control, zero application ) to a maximum application of 200 kg N ha^-1. The relationship between the N doses and the potato yield reached a physical optimal of productivity at a rate of 228 kg N ha^-1. Higher rates (300 kg N ha^-1) resulted in a decrease in yield, generating phytotoxicity for cultivation. This variation allowed us to evaluate the reasoned application method under different nitrogen availabilities (deficiency, optimal and above-optimal) in addition to the variation of the parameters generated.

Urban wetland soil provides ecosystem services (ES) through their functions. Changes in soil properties due to anthropogenic disturbances lead to a loss of soil quality. The aim of this research was to evaluate the effect of nearby anthropic disturbance on the chemical, physical and biological properties of the urban wetland soil. Soil samples were collected from four sites (P1, P2, P3 and P4) located in the Angachilla urban wetland, Chile, according to the magnitude of anthropogenic disturbance. An assessment of the physical and chemical properties of the soil profile was carried out in two sites, P1 and P4. Additionally, chemical and biological properties of the soil were evaluated in the four sites selected. Results from the soil profiles showed that Hz1 of P4 had a higher levels of soil fertility as a result of low anthropogenic disturbance in contrast to Hz1 of P1 (p < 0.05). Relevant differences among sites were observed for P-Olsen, pH NaF, nosZ gene, Nitrate and Na (PC1: 50.5%). Composition of the soil bacterial community in P1 and P4 showed higher richness and diversity. Anthropogenic disturbance on the urban wetland soil leads to a loss of the soil’s organic horizon, as well as its soil quality and, subsequently, its capacity to provide ES through its functions.

Intensive agricultural management affects the physical, chemical, and biological properties of soil, potentially contributing to a decrease in soil carbon storage. In this study, the effects of soil management intensity on soil organic carbon (SOC) content and its labile fractions, i.e., water-soluble organic carbon (OC-sol) and permanganate oxidizable carbon (POXC), were evaluated in a volcanic-ash-derived soil (Andisol) with a very high soil organic matter (SOM) content (>20%). These indicators were associated with water-stable aggregates (WSAs) and biological indicators, namely, earthworm density, cellulase activity, and autoclaved-citrate-extractable (ACE) proteins, related to the decomposition of SOM and its physical protection. The conditions evaluated were secondary native forest (SF), naturalized grassland (NG), no-till (NT), and conventional tillage (CT), considering the last item to be representative of a higher agriculture management intensity. Soil samples were collected by horizon. The SF and NG soil showed higher contents of SOC, OC-sol, and POXC. When comparing the evaluated annual cropping systems, NT showed higher values than CT (p < 0.05) in the first horizon (Hz1), while similar values were found at deeper horizons. The highest cellulase activity, ACE protein levels, and earthworm densities were found in NG and SF. NT also showed significantly higher levels of the aforementioned factors than CT (p < 0.05). A positive and significant relationship was found between the SOC content and WSA (R² = 0.76; p < 0.05) in the whole profile and between POXC and WSA for Hz1 (R² = 0.67; p < 0.05). Soil C storage was affected by the intensity of agricultural management, mainly because of the effect of tillage on structural stability, considering that biological activity synthesizes compounds such as enzymes and proteins that react and adhere to the mineral fraction affecting aggregate stability. The C content stored in the soil is consequently a key indicator with which to regulate SOM and protect SOC.