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It is well known that balanced and optimal mineral fertilization (i.e., nitrogen, phosphorus, and potassium) can increase yield and improve wheat quality. However, there is little scientific knowledge on the specific effect of potassium (K) fertilization on the morphological and qualitative characteristics of rainfed durum wheat under Mediterranean conditions, especially in the context of Algerian agriculture. Therefore, the main objective of this study is to provide crucial information on this important type of durum wheat mineral nutrition for farmers and researchers working in similar areas. The field study was conducted in the Northern Algerian region of Mitidja during the 2020/2021 and 2021/2022 growing seasons. The effect of K fertilization was evaluated within five contrasted rates of K: 0 kg k2O ha−1, 100 kg k2O ha−1, 200 kg k2O ha−1, 300 kg k2O ha−1, and 400 kg k2O ha−1, which were applied on one of the most commonly cultivated cultivars of durum wheat (Simeto). Results showed that increasing potassium levels had a positive and significant impact only on grain yield, spike length, spike neck, and dry matter. Hence, the highest grain yield of durum wheat (2.58 t ha−1) was demonstrated under low K application (100 kg k2O ha−1). This rate leads to an increase in grain yield by more than 0.6 t ha−1, as compared to the unfertilized control. Moreover, the thousand-grain weight of durum wheat was significantly increased by 4.11 g and 1.96 g, respectively, under low and moderate (200 kg k2O ha−1) K-fertilization, as compared to the control. In terms of grain yield quality, low K application provides an increase of 1.21% in protein content as compared to that measured under the control treatment. The major finding confirmed that both growth and yield indicators of durum wheat were globally optimized under low K application. Based on grain yield and evaluated agronomic traits, this research revealed that an applied K rate of 100 kg k2O ha−1 is recommended as the most effective dose to maximize durum wheat yield and quality under Algerian sub-humid conditions.

Wheat–chickpea intercrops are not well studied, despite the importance of these two species in increasing agricultural profitability and ensuring nutritional and food security. The present study aims to assess the intercropping arable system’s services under contrasting field management and climate conditions. Simultaneously, this assessment focuses on the most agronomic and ecological indices widely used in the literature. Durum wheat (Triticum turgidum durum L.cv. VITRON) and chickpea (Cicer arietinum L.cv. FLIP 90/13 C) were cultivated, both in sole crop and intercrop during the 2018/2019 growing season. A field experiment was carried out under controlled conditions at three contrasting pedoclimatic sites and under three levels of N fertilization. Both grain and N yield of mixture crop were significantly higher (+11%) when chickpea and durum wheat were grown together under either low or moderate N application. Soil N availability as compared to the critical level increased by more than 19% from flowering to harvest stage for intercropped wheat under low N application (N-30 and N-60), while it decreased significantly for intercropped chickpea. In rich N soils and under low rainfall conditions (site 1 and 3), intercropping was generally more advantageous for yield (+14%), N yield (+23%), and land use (103 and 119.5% for grain and N yield, respectively) only with reduced N fertilization as assessed using both land equivalent ratio (LER) and land-use efficiency (LUE). Competition dominance was directly affected by changes in climatic conditions over sites; intercropped wheat was more competitive than their respective chickpea under low rainfall conditions. These findings illustrate the crucial role of competitive index assessment in intercropping to promise a robust method for crop N and yield diagnosis during fertilization decision-making.