The effect of the combined use of chemical and organic fertilizers on photosynthesis, growth and yield, in corn and fenugreek intercropping

Background and objectives: The intercropping of corn and fenugreek is an important summer crop due to increase in the efficiency of using resources. Therefore, the aim of the present study was to investigate the effect of combined application of animal, biochar and chemical fertilizers on the growth, photosynthesis and performance of intercropping of corn and fenugreek.
Materials and methods: The experiment was conducted during the agricultural years of 2019 and 2020 at the Agricultural Research Center in Mehran city, located in Ilam province. It followed a factorial experiment and employed a randomized complete block design. The experiment consisted of different cultivation patterns at four levels: pure corn cultivation, pure fenugreek cultivation, and mixed crops with ratios of 2:1 and 6:3 (corn row: fenugreek row). Fertilizer application was also considered with six levels: no fertilizer used (control), animal manure, biochar, recommended NPK, 50% NPK + 50% animal manure, and 50% NPK + 50% biochar. These factors were studied in combination to evaluate their effects on the outcomes of the experiment. In this experiment, traits such as the number of rows per ear, number of grains per row, thousand grain weight, grain yield, and biological yield of corn, as well as the number of pods per plant, thousand grain weight, grain yield, and biological yield of fenugreek, were calculated. To evaluate the profitability of intercropping compared to pure cultivation, indicators such as land equality ratio, area time equation ratio, and land use efficiency were used. Variance analysis of data and mean comparison was conducted using SAS 9.4 statistical software. Graphs were generated using Excel 2013 software.
Results: The main and interaction effects of fertilizer application and intercropping on grain and biological yield, transpiration rate, carbon dioxide concentration under the stomata, and net photosynthesis rate of corn and fenugreek were significant at the 1% probability level. Although intercropping led to a reduction in crop yield and physiological characteristics, the application of biochar fertilizers and cattle manure had a positive impact on these traits, except for the carbon dioxide concentration under stomata, which remained unchanged. The highest grain yields of corn and fenugreek were achieved through sole cropping and with the use of chemical fertilizer and biochar, respectively (914 and 81.7 grams per square meter, respectively). Among the intercropping treatments, the highest grain yields of corn and fenugreek (506 and 58.1 grams per square meter, respectively) were observed in the intercropping of one row of corn to two rows of fenugreek with the use of chemical fertilizers, and in the intercropping of three rows of corn to six rows of fenugreek with the use of biochar, respectively. The indices of land equality ratio, and the efficiency of land use confirmed the benefits of corn and fenugreek intercropping.
Conclusion: The results of the experiment showed that the intercropping of one row of corn: two rows of fenugreek and the use of 50% of chemical fertilizers along with 50% of cattle manure led to the improvement of the yield, and it had the highest indicses of the land equivalent ratio, and land use efficiency. Therefore, this cultivation pattern is recommended to farmers while improving the efficiency of resources and reducing the consumption of chemical fertilizers.