Influence of Crop Rotation and Nutrient Inputs on Soil Properties and Wheat Yield of the Sloping Agricultural Lands in the Plateau Bârlad

Crop rotation and fertilization are two of the most important agrotechnical measures that influence the chemical properties of the soil and its capacity to support stable agricultural production, especially in areas affected by erosion and climate change. The aim of this study was to evaluate the influence of crop rotation and fertilization on the main soil properties (pH, total nitrogen, available phosphorus and potassium, humus content) in moderately eroded cambic chernozems of the Bârlad Plateau, as well as the effect of experimental factors on wheat yield. The research was carried out in the period 2021–2025 in a stationary experiment located on a slope with a slope of 12–13% at “Mircea Moțoc” Soil Erosion Research and Development Station (M.M.S.E.R.D.S.) Perieni. Two wheat cropping systems were analyzed, namely, monoculture and five-year rotation, in combination with five fertilization variants (N0P0, N32P32, N96P96, N128P128 kg ha−1 and 50 t ha−1 manure). The determinations targeted pH, total nitrogen, mobile phosphorus, mobile potassium, humus content in the 0–20 cm and 20–40 cm soil layers and yield. The results highlight the depletion in available nitrogen, phosphorus, and potassium reserves, alteration of soil reaction in monoculture, and significant improvement in N (from 0.1% to 0.19%), P (from 95.5 to 485.5 mg ha−1) and K (from 188.4 to 227.5 mg ha−1) soil content at the time of final sample collection in the five-year rotation. The application of manure as well as the inclusion of legumes and perennial crops in the rotation contributed to the accumulation of organic matter, to the improvement in soil reaction and to the optimization of nutrient cycling. The highest yields, significant at p ≤ 0.001, were obtained with the application of N96P96 2858 kg ha−1 in monoculture and 3689 kg ha−1 in the five-year rotation. The study confirms that long rotations associated with organic fertilization represent an effective strategy for the conservation of agricultural soil fertility in areas vulnerable to erosion and drought.