Soil Physical Properties, Nitrogen, and Crop Yield in Organic Vegetable Production Systems

Abstract

Organic vegetable crops require intensive management, posing challenges for managing N and maintaining organic matter. This experiment was designed to evaluate effects of cropping systems, amendment N sources, and tillage types on soil organic matter, nutrients, physical properties, N availability, and crop yield in organic vegetable production. The experiment was established in 2003 in Puyallup, WA, with cropping system as main plots (fall‐planted cereal–legume cover crop, relay‐planted legume cover crop, and low‐input short‐term grazed pasture), tillage type as split plots (conventional and rotary spader), and amendment as the second split (broiler litter– low C input, and mixed compost–high C input). Vegetable crops were rotated across beds within plots. Yield, available N, soil C, nutrients, bulk density, infiltration, and compaction were measured. Soil C was greater with mixed compost (24 g kg−1) than broiler litter (18 g kg−1), and lower in the low‐input pasture than the cover crop systems. Soil physical properties were most affected by the presence or absence of tillage, and compaction was less with spader tillage. Short‐term N availability was similar between amendments and between fall and relay cover crops. Long‐term N availability was greater with mixed compost compared with broiler litter. Significant differences in crop yield occurred in 12 of 26 harvests. Yield differences among cropping systems were most common, with N availability and competition likely causes. Amendment and tillage affected yield in only 3 of 26 harvests. These results provide farmers with options for organic vegetable production in the maritime Pacific Northwest. Broiler litter and mixed compost soil amendments produced similar vegetable yields. Broiler litter maintained soil C, whereas mixed compost increased soil C. Cover crops did not increase soil C. Nitrogen supply from the fall and relay cover crops were similar. Spader tillage reduced soil compaction compared with conventional tillage.

Potential carbon sequestration and nitrogen cycling in long-term organic management systems

“…The mixed compost was applied after 24–28 weeks of composting and curing in an aerated static pile. The available N supplied by both the amendments were comparable (Cogger et al, 2016). However, the mixed compost supplied 2–5 times more C than the broiler litter.…”

“…The IFSYS organic vegetable systems experiment was established in 2003 as a USDA certified organic field plot at the Washington State University (WSU) Puyallup Research and Extension Center, USA (47°11′ 24″N, 122°19′48″W; elevation 13 m). The experiment is located on an alluvial soil classified as a Puyallup fine sandy loam (coarse-loamy over sandy, isotic over mixed, mesic Fluventic Haploxerolls) (Cogger et al, 2016). The soil had a pH (H 2 O) of 6.4, EC of 0.46 dS m −1 and contained 51% sand, 40% silt and 9% clay.…”

Winter cover crops increase readily decomposable soil carbon, but compost drives total soil carbon during eight years of intensive, organic vegetable production in California

“…Organic production systems rely on management of SOM via applications of compost, manure-based and other non-synthetic fertilizers and green manures (cover crops) to maintain soil fertility and crop productivity [8,9]. Compost applications and cover crops can help counteract the negative effect of intensive vegetable production on SOC [9][10][11][12][13][14][15]. However, because it is well known that soil C changes slowly over time, the long-term effects of management on SOC changes in tillage-intensive vegetable systems are not well understood because few of these studies exceeded 4 years (e.g.…”

“…However, because it is well known that soil C changes slowly over time, the long-term effects of management on SOC changes in tillage-intensive vegetable systems are not well understood because few of these studies exceeded 4 years (e.g. Cogger et al [15]). Because it has already undergone partial decomposition, mature compost contributes relatively stabilized C to soil contributing slowly available SOC, while cover crops contribute to actively cycled SOC pools [11,[16][17][18].…”

Changes in soil macropores: Superposition of the roles of organic nutrient amendments and the greenhouse pattern in vegetable plantations

“…Similar results were obtained by Papadopoulos, Bird, Whitmore, and Mooney () with X‐ray computed tomography (CT) scanning in the UK. In addition, several researchers have examined the effect of organic fertilization on soil pores under other beneficial modes of tillage (Cogger, Bary, Myhre, Fortuna, & Collins, ; Loaiza Puerta, Pujol Pereira, Wittwer, van der Heijden, & Six, ). For example, Loaiza Puerta et al.…”