Long-term yields of oilseed rape and winter wheat in a short rotation alley cropping agroforestry system

Abstract

Alley cropping agroforestry systems (ACS) are ascribed to have manifold positive ecological effects; nevertheless their application is still limited due to uncertain productivity of the agricultural crop, especially in the tree-crop competition zone. Therefore, this study investigated the variability of oilseed rape and winter wheat yield, respectively, at different distances from the tree strip edge in 2016 and 2017 in an ACS established in 2008 in northern Germany. The ACS consisted of strips of fast-growing poplars alternating with narrow (48 m) and wide (96 m) crop alleys, each with a crop rotation including winter oilseed rape and winter wheat. Each tree strip contained 6 rows of poplars with a density of 10,000 trees per ha. Moreover, multi-year (2009-2016) crop yield data of oilseed rape and winter wheat in the narrow and wide crop alleys were compared with those of a corresponding non-agroforestry control field. In general, crop yields observed in 2016 and 2017 in the narrow crop alleys at 1 m from the tree strip edges were on average 77% (oilseed rape) and 55% (winter wheat) lower than in the middle of the crop alley. One reason for low yield close to the tree strips might be the leaf litter coverage of the seedlings in autumn. Leaf litter deposition was highest at 1 m on the windward and the leeward side of the tree strips in 2015 and on the leeward side in 2016, respectively. However, the average long-term crop yields of the narrow crop alley, the wide crop alley and the control field did not differ substantially among each other. Although oilseed rape and winter wheat yields were lower close to the tree strips, this yield reduction did not negatively influence the average long-term crop yields of the ACS. Keywords Alley cropping Á Crop yields Á Winter wheat Á Oilseed rape Á Yield variability Á Competition zone Á Long-term yield Á Leaf litter

Trade-Off between Energy Wood and Grain Production in Temperate Alley-Cropping Systems: An Empirical and Simulation-Based Derivation of Land Equivalent Ratio

“…At Wendhausen, small variation was noticed within crop yields from APs and MPs, although the absolute values would indicate a slight yield advantage stemming from the windward arranged plots, caused mainly by the leaf litter deposition [20]. Significant differences at Wendhausen were observed between the APs and MPs, with crop yield advantages inclining toward the latter plots.…”

“…Significant differences at Wendhausen were observed between the APs and MPs, with crop yield advantages inclining toward the latter plots. The reduced crop yield in APs was correlated with tree height (i.e., more than 6 m), hence, higher tree shading causing crop developmental delays up to 7 m away from the tree strips [20].…”

“…3 [20] 30 [21] Alley-cropping system Tree species Poplar (Populus nigra L. × P. maximowicii Henry, clone "Max I"), with cultivated cropped alleys Tree rotation cycle 6-year 4-year (1st rotation) 3-year (2nd rotation) Tree row orientation North-South North-South Area tree strips (m 2 ) * 10 × 225 [20] 10 × 660 [21] Tree spacing (m) 2 × 0.5 [20,22] 2.6 × 0.4 Tree planting density (ha −1 ) 10,000 [20,22] Monthly values for mean air temperature and total rainfall during the two years of investigation were used for creating Walter-Lieth climate diagrams ( Figure A1) in order to gain insight into the compound effects that influence the growth of trees and crops.…”

“…However, since the woody biomass measurements showed no significant differences between the two lee-and two wind-ward plots, the woody biomass was analysed considering four replicates. For the model calibrations, we retrieved information about the trees (planting density, management, yield, DOYplant, DOYharvest), crops (management, yield, DOYsow, DOYharvest), and soil physical characteristics (texture, structure, porosity, bulk density, organic matter) reported by Lamerre et al [23] and Swieter et al [20] for the site at Wendhausen and by Kanzler and Böhm [21] at Neu Sacro. This information, together with model ecophysiological parameters based on bibliography and expert knowledge, as instructed in Graves et al [29], Keesman et al [31], Burgess et al [33], and Wösten et al [36], created the data set used for the calibration of the model.…”

“…">Experimental SitesData used for this study was gathered in 2016 and 2017 at two short-rotation alley-cropping systems (ACSs) established near Wendhausen (Lower Saxony) and Neu Sacro (Brandenburg), Germany. The ACS at Wendhausen consists of nine tree strips having a width of 10 m (without the so-called buffer zone, a distance of about 1.5 m allocated between the tree strip and crop alleys for the agricultural machinery) and a length of 225 m, with agricultural alleys of 48 m and 96 m width between the tree strips [20]. The ACS at Neu Sacro consists of seven tree strips having a width of 10 m (without the buffer zone of 1.5 m) and a length of 660 m, with agricultural alleys of 24 m, 48 m, and 96 m width between the tree strips [21].…”