Modelling the yield and profitability of intercropped walnut systems in Croatia

Abstract

In Croatia, farmers are showing increasing interest in establishing walnut orchards for nut production on arable land due to higher anticipated net margins. One way to address the lack of profitability in the initial years when nut yields are low may be to plant arable intercrops. The anticipated impacts of this practice were assessed using a biophysical simulation model (Yield-SAFE) to determine the growth and yield of crops and trees in arable, orchard, and silvoarable systems, and an economic farm model (Farm-SAFE) was used to assess their profitability. The walnut orchard and the intercropped orchard systems were simulated assuming tree densities of 170, 135, and 100 trees ha−1, to determine the profitability and break-even date of the systems. The biophysical simulation predicted a decline in arable intercrop yields over time in all tree density scenarios. However, analysis of productivity of intercropped systems showed that intercropping was more productive than separate arable and walnut production for all tree density scenarios. From financial aspect, the return from intercropping helped to offset some of the initial orchard establishment costs and the arable intercrop remained profitable until the sixth year after tree planting. The modelling predicted that a system with 170 trees ha−1 that included intercropping for the first 6 years provided the greatest cumulative net margin after 20 years. The financial benefit of intercropping over the first 6 years opposed to monoculture walnut fruit production appeared to be consistent across the three tree densities studied. These results suggest that silvoarable agroforestry is profitable approach to establishing walnut orchards.

The Effect of Tree Spacing on Yields of Alley Cropping Systems—A Case Study from Hungary

“…These were also the most productive cases when looking at the yields on a square metre basis, so even though the ratio of sown area was lower, the higher yields compensated the ’field loss’ on a hectare basis. Likewise, Žalac et al [ 15 ] also reported high relative crop yields in a grain maize–barley–rapeseed rotation in a walnut alley cropping system, with LER values 1.05–1.14 in years 1, 4 and 7, predicted by the Yield-SAFE model. In that study, a simulation of maintaining the system for 20 years resulted in LER 1.38–1.53 depending on the number of trees per hectare (170 and 100 trees, respectively).…”

“…Another case is when fruit trees are grown in the alley cropping system, and thus no data on timber is recorded. In research conducted in Croatia [ 15 ], maize, barley and rapeseed were grown between allies of walnut trees with different tree planting densities per hectare (170, 135 and 100 trees ha −1 ), using the Farm-SAFE and Yield-SAFE models. However, the analyses focused on walnut fruit and not on the timber production.…”

“…Thus, it was only true for the wider row spacings (>9 m). This is most likely due to enhanced competition between trees and crops for the resources, as trees grow with age [ 15 ].…”

“…To be able to calculate economic return more studies are required on the productivity of alley cropping systems [ 14 ]. On the other hand, fruit growers may implement intercropping between fruit trees for annual income before the trees start to produce fruits or nuts [ 15 ]. Whatever the case may be, one must be careful when designing and implementing such systems, as there are several complex ecological processes that occur which have to be understood, to make sure that ecosystems are rather improved and not damaged [ 16 ].…”

“…Black locust is a multifunctional nitrogen-fixing tree species which is of great international interest; alongside triticale, both species play an important role in the changing climate, with their drought-tolerant attributes and due to their potential in marginal sites and their resistance against pests and diseases. Results can be relevant for agroforestry research worldwide, but mainly in temperate climates, as such studies are particularly scarce [ 15 , 22 , 23 ]. Furthermore, the results could serve as valuable inputs for biogeophysical and economical modelling, as well as for calculating climate change mitigation potential.…”