Is sustainable soil management good for farmland birds?

Conventional arable systems are designed to produce food at high levels of efficiency, but usually require large amounts of energy and chemical inputs per unit of land, with cascading detrimental effects throughout the field agroecosystem. Thus, agricultural intensification processes have been linked with the decline of farmland bird and invertebrate populations, and with arable soil degradation. Today, agricultural policies and practices are seeking to develop arable systems that are less dependent on these inputs, and sustainable soil management (SSM) practices have been introduced as a way to maintain soil as a healthy living system and support agricultural production.

This thesis aimed to assess if cover crop and green waste compost amendment have the potential to benefit farmland bird populations during breeding season. In particular, the thesis focused on the association of these practices with belowground and aboveground invertebrate abundance and assemblages, chick food availability, and Skylark Auleda arvensis territory settlement during breeding season. This study took place at Hope Farm, a commercial arable farm owned by the RSPB that has been operating since 2015 a trial of the effects of SSM in three experimental split-plot fields.

Cover crops were shown to have a positive association with belowground invertebrate abundance and soil biological quality, and with the abundance of canopy dwelling invertebrates, suggesting that this practice may support invertebrate populations. Green compost, albeit strongly increasing soil organic carbon content, did not have an effect on invertebrates. Increased abundance of invertebrates was not reflected by an increase in in-field food availability to breeding birds, and the distribution of Skylark territories did not vary among plots with different soil treatment management over the course of five years. Thus, the results of this thesis suggest that cover crops and green compost did not benefit farmland birds at Hope Farm during summer. This thesis highlights the importance of evaluating the effects of individual in-field soil management practices expected to target broad environmental goals.