The use of the ingrowth core method for measuring root production of arable crops - influence of soil conditions inside the ingrowth core on root growth

The ingrowth core method can be used to measure root gross growth (i.e. roo t production). A mesh bag filled with root free soil is buried into the roo t zone. After about 14 days, the bag is pulled out and root length inside t he core can be determined. An objection against this method is the inabilit y to obtain the same soil conditions inside the bag as outside, which can r esult in different root growth pattern in the ingrowth core compared to the bulk soil. To study this, mesh bags were buried in a stand of oilseed rape and were filled with soil at different nitrate, phosphate, moisture, and b ulk density levels. Results showed that root growth was only influenced by a high nitrate content and a high soil density in the coes, which resulted in higher and lower root length densities (RLD), respectively. In a long-te rm ingrowth experiment similar root length densities in the cores and in th e bulk soil were measured, indicating that there were no root growth enhanc ing or impeding conditions inside the ingrowth cores. The conclusion is dra wn, that the ingrowth core method gives reliable results, provided the N co ntent and the soil density inside the bags are to the bulk soil.