Organic Amendment and Rotation Crop Effects on the Recovery of Soil Organic Matter and Aggregation in Potato Cropping Systems

Abstract

der et al., 1994). Water soluble carbohydrates directly stabilize aggregates (Angers and Mehuys, 1989) and Soil structural degradation is common in intensively cultivated have been strongly correlated (r ϭ 0.74) with aggregaecosystems due to the depletion of soil organic matter (SOM). We tion (Haynes and Swift, 1990). investigated the mechanisms by which different frequencies of organic amendment application and rotation crops restore C, N, and aggrega-Green manure crops increase soil C inputs, but their tion in gravelly loam soils used for potato production. A single amendeffects on SOM equilibrium and aggregation may occur ment application [FIRST; 22 Mg ha Ϫ1 compost and 45 Mg ha Ϫ1 beef slowly because background levels of soil C are relatively cattle (Bos taurus L.) manure] did not affect total C in 1996 and inhigh and spatially variable (Robertson et al., 1993, 2000). creased it by 28% in 1997 relative to unamended plots (NONE); light Long-term annual compost and manure applications infraction (LF) C accounted for 56% of this increase. Plots in which crease SOM and structure (Sommerfeldt et al., 1988; amendment was suspended for 1 yr (SASP) following 4 or 5 yr of Gilley and Risse, 2000); however, annual applications annual application had more total C in 1996 (28%) and 1997 (46%) are expensive (Araji et al., 2001) and thus not widely relative to NONE. A green manure crop consisting of oat (Avena sativa utilized in Maine. Applying organic amendments less 'Porter'), pea (Pisum sativum 'Trapper'), and hairy vetch (Vicia villosa than annually would be more cost effective if they could Roth) grown in 2-yr rotation with potatoes (Solanum tuberosum L.) reverse the negative effects of potato production. increased soil C in 1997 (25.9 vs. 23.9 g kg Ϫ1), LF properties in 1996 and 1997, and water soluble carbohydrates (WSC) on several sample Minimizing the frequency of organic amendment apdates relative to an oat rotation crop. Large aggregate (2-6.5 mm) plication depends on predicting the number of applicastability in 1996 and 1997 and medium aggregate (1-2 mm) stability tions necessary to halt declines in SOM and structure in 1997 were increased by FIRST relative to NONE. Total soil C was and, once the decline stops and amendments are no more strongly related to medium (r ϭ 0.65 in 1997) and large (r ϭ longer applied, whether the benefits of amendment per-0.51 in 1997) aggregate stability than LF or water soluble carbohydrate sist. Increases in soil C and total aggregation have been fractions. Compost and manure influences occurred rapidly and were reported in potato cropping systems after a single compersistent, demonstrating that annual applications are not necessary post and manure amendment application (Porter et al., to reverse soil degradation. 1999), but relationships between organic matter pools and aggregation still require elucidation. Effects of organic amendments may last for a century or more on Growing year Amendment and

Residual Effects of Fresh and Composted Dairy Manure Applications on Potato Production

“…Nutrient cycling and accumulations in potato production systems are also important to understand, as applications of fertilizers often need to be adjusted to compliment the nutrient supply from the manure source. Grandy et al (2002) found that fields receiving 16 t ha −1 cattle manure 6 years prior to potato production did not affect soil bulk density, but soil carbon content increased by 46% and medium and large soil aggregate content increased in comparison to the field that had not received manure. Curless et al (2005) found that potatoes consumed excess phosphorus (P) from fertilizer sources, but not from manure sources.…”

Influence of 10 years of conservation tillage on some biological properties of a fine sandy loam in the potato phase of two crop rotations in Atlantic Canada

“…Comparisons for MWD, compared between the present and earlier study, showed that the MWD remained B1.0 for the 2-yr conventional tillage, but increased from 1.3 to 1.6 for the 3-yr conservation tillage. Grandy et al (2002) and Carter et al (2003) showed that organic amendments and rotation crop effects can improve soil aggregation even in short-term potato rotations. This was expressed by increases in the proportion of large ( 1 and 2 mm) aggregates in the 3-yr rotation (Fig.…”

“…Length of crop rotation and frequency of potato cropping, use of leguminous companion-crops, and type of soil management system have an important bearing on soil biological parameters, such as soil organic matter fractions (Grandy et al 2002;Carter et al 2003), soilborne diseases (Leach et al 1993;Peters et al 2004Peters et al , 2005, root lesion nematode populations (Kimpinski et al 2000;, and microarthropod communities (Fox et al 1999;Carter and Noronha 2007). In many cases, the above changes in soil biological properties take a significant time period (e.g.,5 yr) before they become evident, and thus require relatively long-term studies for their evaluation .…”

“…Soil organic matter can influence soil biological parameters such as soil structure and soil microbial and faunal diversity. Conservation practices (e.g., reduced tillage, organic amendments, rotation crops) in potato cropping systems can increase soil C and N resulting in concomitant improvements in soil structure, increases in soil organic matter fractions, potato yield stability, and soil fauna (Carter and Sanderson 2001;Grandy et al 2002;Mallory and Porter 2007). However, few data are available that describe long-term effects of tillage management on the dynamics of soil biological properties.…”

“…Intensively cultivated 2-yr potato rotations appear to be viable in regard to soil parameters if suitable soil amendments are applied to maintain soil organic matter levels and soil structural quality (Grandy et al 2002). Potato yield parameters can also be stabilized under 2-yr rotations by the use of appropriate organic amendments (Mallory and Porter 2007).…”