Soil Nutrient Balance and Stock on Smallholder Farms at Agew Mariam Watershed in Northern Ethiopia

Abstract IntroductionSoil nutrient balance is used to evaluate the state of soil fertility, rate of nutrient depletion, sustainability of land productivity, the environmental wellbeing of an area, and to take appropriate management decisions. This study was conducted to quantify soil nutrient balance and stocks on smallholder farms at the Agew Mariam watershed in northern Ethiopia in the 2020/21 main season.MethodsInflows and outflows of nitrogen (N), phosphorus (P), and potassium (K) into, and out of barley, tef, and wheat farms were determined through, field measurement, laboratory analysis, and interviews. The balance quantification was done by subtracting nutrient outputs from the inputs. ResultsThe N partial balance of barley, tef and wheat was -66, -9.8, and -50.7 kg ha-1 yr-1 respectively. The P balance was also -5.9, 0.9, and -2.6 kg ha-1 yr-1 for barley, tef, and wheat respectively. Whereas, K balance was -12.3, -3.2, and -5.4 kg ha-1 yr-1 from barley, tef, and wheat respectively. The balance results revealed that N, P, and K had negative values except for P in tef. Grain yield and crop residue removal were the major paths of nutrient loss. The stock of N was 1295, 1510, and 1240 from barley, tef, and wheat kg ha-1respectively. While, the P stock was 63, 18.7, and 27.5, kg ha-1 from barley, tef, and wheat farms respectively. Similarly, K stock was 1092.7, 1059.4, and 1090.6 kg ha-1 from barley, tef, and wheat cropping systems respectively. ConclusionsReversing the imbalance between inflows and outflows via adding organic and inorganic fertilizers is critically essential for the study area.