Evaluation of the Competitive Indices and Economical Adavantage of Corn (Zea mays L.)- Bean (Phaseolus vulgaris L.) Intercropping under the influence of Tillage Levels, Crop Residues, and Planting Patterns

IntroductionIntercropping is considered as one of the components of sustainable agriculture, where two or more species are grown in the same location to take advantage of the beneficial effects between the species. The competition among species for resource use can be facilitative, conflicting, or neutral. In many intercropping systems, plants from the legume and cereal families are cultivated with the aim of creating a complementary relationship between species and to enhance resource use efficiency. One practical way to increase organic matter in agricultural lands is through conservation tillage and returning plant residues to the soil. Corn (Zea mays L.) is the third most important cereal in the world, after wheat and rice. Pinto beans (Phaseolus vulgaris L.) are among the most consumed legumes, playing a crucial role in providing the protein that humans need. The purpose of this research was to evaluate the performance, competitive indicators, and economic benefits of intercropping of corn and beans influenced by tillage systems, crop residues, and planting patterns in the conditions of Shahrekord.Materials and MethodsThe experiment was performed using split-split plot based on a randomized complete block design with three replications in Agricultural Research Field of Shahrekord during 2016–2018. Tillage with two levels (minimum, and no-tillage) and three levels of crop residues (30, 60, and 90% of straw yield of wheat) and five intercropping patterns including corn and bean sole cropping, corn and bean ratio with 2:2, 3:1 and 1:3 were considered as main, sub and sub-sub plots, respectively. After measuring the yield of corn and beans, in order to evaluate the efficiency and competition in intercropping, the indices of land equivalent ratio, relative crowding coefficient, aggressivity and competition ratio were calculated. Also, in order to measure the economic usefulness of intercropping, system productivity index, Intercropping Advantage, and Monetary Advantage Index were used.Results and DiscussionBased on the results obtained, the interaction of tillage × crop residues × plant patterns had a significant effect on the yield of corn and beans (P ≤ 0.05). Based on the average comparison results, the highest corn yield was obtained in sole corn cultivation under no-till conditions and using 60% of residues in the second year of the experiment (1.9317 kg ha-1). The yield of bean seeds, the highest yield was related to sole bean cultivation in low tillage conditions and the use of 60% plant residues (2933.91 kg ha-1). The interaction of tillage × crop residues × plant patterns on total land equivalent ratio was significant (P≤0.05). The plant pattern of 2 corn: 2 beans had the highest amount of LER (1.71) compared to other intercropping patterns. The maximum value of total relative crowding coefficient and competition index for corn was obtained in the plant pattern of 2 corn: 2 beans. Also, the positive values of the aggressivity index for the corn showed the competitive advantage of this plant compared to beans. The corn canopy has a larger volume and height compared to the bean canopy, so corn is a stronger competitor in absorbing light and other resources than beans. The corn canopy has a larger volume and height compared to the bean canopy, so corn is considered a stronger competitor in absorbing light and other resources than beans. The system productivity index was positive across all intercropping ratios, indicating the overall effectiveness of intercropping. The highest intercropping advantage (5859.42) and monetary advantage index (5988.62) were observed in the 2 corn: 2 beans planting pattern. The increased monetary advantage index in this ratio can be attributed to the higher land equivalent ratio and total relative crowding coefficient achieved in this treatment.ConclusionAccording to the results obtained from the evaluation of the land equivalent ratio and the relative crowding coefficient, intercropping advantage and monetary advantage index, it can be stated that the 2 corn: 2 bean planting pattern was superior in terms of competition and economic usefulness compared to other intercropping patterns. Based on the findings of this research, the positive values of the aggressivity index and the increase in the competition index indicate a competitive advantage of corn over beans in intercropping. Therefore, it can be said that the 2 corn: 2 beans, in addition to creating diversity and sustainability through maximizing the biological potential of the species, is significantly effective in enhancing financial advantage and the efficiency of using agricultural lands.