Nitrogen, irrigation, and alley management affects raspberry crop response and soil nitrogen and root-lesion nematode dynamics
Kuchta, S., Neilsen, D., Zebarth, B.J., Forge, T., Nichol, C. (2021). Nitrogen, irrigation, and alley management affects raspberry crop response and soil nitrogen and root-lesion nematode dynamics. Soil Science Society of America Journal, [online] 85(4), 1139-1156. http://dx.doi.org/10.1002/saj2.20190
Plain language summary
Commercial raspberry production in the Fraser Valley of British Columbia includes the use of synthetic fertilizers and manures to ensure that plants have adequate nutrients, particularly nitrogen, to produce high yields of quality fruit. The application of nitrogen in excess of crop uptake can, however, result in nitrate leaching to groundwater. As well, nitrogen applications can have non-target effects on populations of pests that may have longer-term consequences for production. In an effort to improve raspberry nitrogen management practices, a field experiment was set up to assess the influences of different nitrogen fertilizer application rates, types of fertilizers (synthetic vs manure), methods of scheduling irrigation, and the presence or absence of between-row cover crops, on overall crop vigor, berry yields, nitrate in soil, and populations of root-lesion nematodes which are damaging soil-borne pests of raspberry roots. The results indicated that variation in nitrogen application rate and type of fertilizer (synthetic vs manure) had little effect on raspberry vigor or yields. This was attributed to a relatively high amount of nitrogen being made available to plants from sources other than the applied fertilizer, such as atmospheric deposition and soil organic matter. As well, large root-lesion nematode populations may have suppressed raspberry growth in fertilized plots. Scheduling irrigation based on weather rather than on a calendar basis reduced water use by about 50% without affecting crop performance. Similarly, the presence of a perennial grass between-row cover crop reduced nitrogen accumulation in soil without affecting crop performance. Taken together, these findings demonstrate that it is possible to adopt practices that reduce risks of nitrate leaching without impacting raspberry production.
There is a need to improve raspberry crop nitrogen (N) management practices, particularly when grown over aquifers vulnerable to nitrate (NO3) leaching. This study quantified the effects of N, irrigation and alley management strategies on berry yield, indices of crop vigor and N status, growing season soil N dynamics, and root-lesion nematode (RLN) population dynamics under red raspberry production in British Columbia, Canada. Conventional management (100 kg N ha−1 surface broadcast on the row, clean cultivation of alleys, and drip irrigation for a fixed duration regardless of evapotranspiration [ET]) was compared with different mineral fertilizer N rates, application of N as manure, seeding the alley to either a perennial forage grass (perennial ryegrass [Lolium perenne L.] and ‘Bridgeport II’ chewings fescue [Festuca rubra subsp. commutate]) or an autumn-seeded spring barley crop, or ET-scheduled irrigation. In addition, the combination of ET-scheduled irrigation plus fertigation of a reduced rate of N was compared with conventional practices at a reduced N rate. There was little or no crop response to N source and rate, a finding attributed primarily to high nonmanaged N inputs, and possibly also to RLNs present at population densities (grand mean = 4 per cm3 soil) expected to suppress raspberry growth. ET-scheduled irrigation reduced water use ∼50% compared with fixed-duration irrigation without compromising crop performance. The perennial forage grass in the alley reduced soil mineral N but not yield. Taken together, these findings demonstrate that more environmentally sustainable raspberry production can be achieved through integrated management systems even in soils vulnerable to NO3 leaching.