Intercropping cover crops with a poplar short rotation coppice: Effects on nutrient uptake and biomass production

Abstract

The risks of soil erosion and nutrient leaching can be considered appreciable in short rotation coppices especially in the first growth phases because of the absence of any plant cover. The temporary intercropping with legumes or grasses used as cover crops can help to overcome these environmental issues. The present research work aims to evaluate the effects of the introduction of cover crops in a short rotation poplar (Populus deltoides W. Bartram ex Marshall) with two-year harvest cycle. The plantation was located in a Typic Xerofluvent, silty-loam soil of the coastal Central Italy. Two different species of cover crops, Trifolium subterraneum L. (TS) and Lolium perenne L. (LP), were compared along with an untreated control, colonised by spontaneous vegetation (CO). Several plant and soil parameters were evaluated: the above ground biomass and nutrient accumulation for the three different soil cover types, the nitrate and water content in two soil layers (0.00-0.30 and 0.30-0.60 m), the poplar yield and nutrient content in branches and leaves.TS returned to the soil about 70 kg ha -1 of nitrogen at the end of its biological cycle, thanks to the high N content (over 2%) and to the noticeable amount of dry matter produced (3.46 t ha -1 of dry matter). This value was considerably higher than those of the LP (23 kg ha -1 of N) or CO (10 kg ha -1 ). The different amount of nitrogen returned to the soil affected both nitrate concentration in topsoil (0.00-0.30 m) and accumulation of nitrogen in poplar organs. Concerning phosphorous, the differences among treatments were less evident and the amount of P returned to the soil ranged from 2 (CO) to 10 (TS) kg ha -1 . However, the effect of soil cover type on P uptake in poplar was still appreciable. Generally, the soil water content was slightly affected by the soil cover types. Indeed, the differences between the cover crops and the control became significant only in the shallowest soil layer and over the summer season. In the first year, LP induced a significant decrease in poplar yield (10.1 t ha -1 of dry matter) in comparison with TS (14.7 t ha -1 ) and CO (13.4 t ha -1 ), whereas in the second year there were no significant differences among treatments due to the weak regrowth of cover crops.These results show how to make it feasible a long lasting coexistence between cover crops and SRC, a clever design of agro-forestry systems is therefore needed.

Chestnut Response to Organo-mineral and Controlled-Release Fertilizers in Rainfed Growing Conditions

“…18:5:13 did not stand out so much from those of the control treatments, likely due to the competition for soil available N by the herbaceous vegetation. As previously reported for several other fruit species, cover crops tend to reduce fruit production if competition with trees for resources is high (Hoagland et al 2008;Gucci et al 2012;Silvestri et al 2018). Thus, the use of N seems to be more efficient in tilled than in cover cropped orchards, at least in the short term (4 years) while the increasing pool of organic matter can lead to a negative balance between mineralization and immobilization (net immobilization).…”

A functional trait framework for integrating nitrogen‐fixing cover crops into short‐rotation woody crop systems

“…In tropical regions, N‐fixing cover crops had null or negative effects on tree growth; these studies provided limited information about ecosystem—soil or plant—N status (Little et al, 2002; Lulandala & Hall, 1987; Mendham et al, 2004). In temperate regions, N‐fixing cover crops had mixed effects on tree growth (Table 1) (Cogliastro et al, 1990; Haines et al, 1978; Malik et al, 2001; Smethurst et al, 1986), but there is evidence that winter crops are less likely to compete with trees compared with perennials or summer crops (Haines et al, 1978; Redmon, Rouquette, Goad, et al, 1997; Redmon, Rouquette, Smith, et al, 1997; Silvestri et al, 2018; Smethurst et al, 1986; Van Sambeek et al, 1986). The evidence for better complementarity in intercrops with deciduous hardwoods than evergreens was rather weak, but few studies provided multiyear or rotation length comparisons.…”

Cover Crop Introduction in a Mediterranean Maize Cropping System. Effects on Soil Variables and Yield

“…The differences between CO and TR almost disappeared in the underlying layer (30-50 cm) since the tillage did not allow the residues of CC to reach this depth and therefore the growth of the nitrogen immobilization did not occur [9].…”

“…CCs are able to affect the behaviour of subsequent crops by acting on many soil characteristics and, at the same time, they can drive dynamics of a large number of ecological processes, which are extremely relevant from an environmental point of view. Among the effects attributable to the former, we can mention: (i) soil humidity conservation [6], (ii) improvement of soil structure and aggregate stability [7], (iii) weed suppression [8], (iv) increased availability of nutrient [9], (v) enhancement of soil microbial environment and wildlife category [10]. Conversely, (i) soil erosion control [11], (ii) reduction of nutrient losses via run-off and leaching [12], (iii) increasing of organic C (carbon) content in soil [13] can be included in the second category.…”