Issue link: https://read.dmtmag.com/i/473131
www.goodfruit.com GOOD FRUIT GROWER MARCH 15, 2015 47 AVOID THE ORCHARD OF NO RETURN WITH SOIL FUMIGATION CALL TODAY TO SCHEDULE YOUR APPLICATION: Northwest Washington: Tim Purcell 360-630-4285 Yakima Valley: Robert Rauert 509-728-2004 Columbia Basin: Jason Rainer 509-731-5424 Oregon: David Sbur 971-563-8848 Office 360-225-3588 Soil fumigation in replanted orchards produces earlier, bigger yields and higher profits—not just in the early years, but over the life of the orchard. Trident Agricultural Products can help you create that orchard. With 30+ years of experience, Trident is the Pacific Northwest's soil fumigation specialist. Trident offers custom application of Telone ® C-17, Telone C-35 and Pic-Clor 60. Applications can be made in tree fruit, hops, grapes, berries and nursery crops. ® Trademark of the Dow Chemical Company ("Dow") ϐǤ restricted use pesticide. Always read and follow label directions. A soil's cation exchange capacity (CEC) is a measure of the net negative charge of dry soil and, therefore, is a measure of the amount of positive nutrients that can be stored. Soils with a low CEC have a low net negative charge and do not hold positive nutrients in the soil as well as do soils with a high CEC. Organic matter, with its neg- ative charge, can help improve soils with low CEC. Organic matter also decreases the fixation of phosphorus and potassium in the soil and forms metal-organic complexes that stabilize the micronutrients that otherwise might not be available for plants. Organic matter and soil stability Organic matter controls the stability of soil so that the aggregates do not collapse or erode when wetted quickly. Organic mulch or growing plants protect the soil from heavy rain, so a hard crust does not form when the soil dries. Large aggregates (more than 2 mm) are held together by a fine network of root and fungal hyphae, and fragments of plants and dead micro- bial cells become encrusted with clay par- ticles to form stable smaller aggregates. The organic matter also encourages soil animals to produce tunnels that enable soil, water, and roots to move through soil. Silt and clay soils with less than 1.5 per- cent organic matter have small, closely packed aggregates and many very small pores. When wetted, any poorly struc- tured, large aggregates break down, or slake, into micro-aggregates. When dry, the micro-aggregates block pores that are too small for water to move through, causing the soil to become poorly aerated when wet and excessively hard when dry. How to increase organic matter As you prepare the soil in summer and fall before you plant trees, till (rip and/or cultivate) the soil then grow ryegrass, but kill it in winter. Once the trees are planted, do not till the soil again, as repeated tillage oxidizes (burns) organic matter and decreases activity of beneficial organisms, worsening the soil structure, and the supply of water, air, and nutrients. Each year, manage the soil carefully with a cover crop or organic mulch to: —add organic residues —protect the surface of the soil from heavy rain —decrease loss of water by evaporation —increase storage of water —increase the activity of beneficial biota in soil In winter, allow weeds to grow. Throw the green residues of the weeds onto the tree rows when you slash. In spring and summer, use herbicides to kill the weeds in the tree rows so that the weeds do not compete with the trees for water and nutrients. The green and dead weeds on the soil surface protect the soil surface from heavy rain, and the dead roots add organic matter and maintain a soft, stable, and porous surface soil. • Dr Judith Tisdall is a soil scientist and a former senior lecturer in soil science at La Trobe University, Melbourne, Australia. Bas Van den Ende is a tree fruit consultant in Australia's Goulburn Valley.