Nutrient dynamics from surface‐applied organic matter amendments on no‐till orchard soil

Abstract

Advancing conservation agriculture depends on understanding nutrient dynamics of organic matter amendments (OMA) on no‐till soil. This field incubation study compared surface‐applied composted dairy manure (CM), green waste compost (GWC) and an unamended control from March to September in 2015 and 2016 using a RCBD in a California almond (Prunus dulcis) orchard. Measurements included OMA nutrient release rates, changes in soil organic carbon (SOC), total N (TN) and inorganic N, P and K availability using in‐season soil sampling and collection of ion exchange resin (IER) membranes from 0 to 10 cm depth, and cumulative N and P availability using soil IER cores from 0 to 50 cm depth. We hypothesized OMA sources with a lower initial C:N increase soil N availability, greater soluble phosphorus (P) and potassium (K) concentrations increase P and K availability, and all OMA sources increase SOC with the greatest N recovery in the TN pool. No differences were observed in C, N and P release rates, while the K release rate was the greatest. In‐season N availability showed no effect but P and K availability differed as evidenced by greater IER adsorption and soil extractable P and K. Both OMA sources significantly increased in SOC and TN. Net N mineralization from OMA sources ranged from 0.7% to 8.0% of applied N and total N recovery in TN and inorganic N pools increased based on the initial C:N. These results advance our understanding of nutrient dynamics while conserving the soil due to the no‐till practice of surface‐applied OMA.

Annual compost amendments can replace synthetic fertilizer, improve soil moisture, and ensure tree performance during peach orchard establishment in a humid subtropical climate

“…The site conditions and historical management may also contribute to the utility and ecosystem services of amendments ( De Leijster et al., 2019 ) since compost applications increased OM in the replant location, but not the virgin location compared to the control. Nevertheless, increasing OM in the replant location after only several years agrees with other studies which have observed increased soil organic carbon after adding OM amendments to the soil surface ( Villa et al., 2021 ; Khalsa et al., 2022 ). On the other hand, more than four years may be necessary to observe changes to OM or tree parameters when using amendments ( Neilsen et al., 2014 ; Toselli et al., 2019 ) and the four-year duration of this study is insufficient to understand the treatment effects over the lifetime of the orchard.…”

Long‐term compost use and high frequency low concentration fertigation reduce N2O emissions from a California almond orchard

“…In our study, the compost-amended orchard soil had ∼61% higher total C content and 63% higher total N content than the No Compost treatment (Table 1). This increase in total C and N aligns with other findings on effects of OM amendments, such as composted dairy manure, chicken litter, and yard green waste, in almond and peach orchards (Khalsa et al, 2022;Martínez-Blanco et al, 2013;Preusch & Tworkoski, 2003). Soil bulk density tended to be lower in our compost amended orchard soils (Table 1), which is consistent with previous work showing that organic amendments reduce bulk density and compaction (Arvanitoyannis & Kassaveti, 2007;Cayuela et al, 2004;Mujdecİ, 2011;Peck et al, 2011).…”

“…In the current study, we posit that the reduced N 2 O emissions associated with increased soil C in compost may be a result of increased microbial immobilization of available N (Khalsa et al, 2020(Khalsa et al, , 2022Senbayram et al, 2012). We examine this supposition here.…”

“…The application of compost, the product of accelerated aerobic decomposition of organic waste under controlled conditions, increases soil organic matter (SOM), thereby improving soil aggregation, water infiltration and holding capacity, resistance to erosion, and net primary productivity of the crop (Diacono & Montemurro, 2010; Tautges et al., 2019). Recent studies about organic matter (OM) amendments have focused on increasing nutrient availability or retention, improving soil structure and enriching soil C sequestration (Khalsa et al., 2022; Tautges et al., 2019).…”

“…To quantify the potential benefits and tradeoffs of OM amendments like compost in agricultural soils, changes in both SOC content and GHG emissions must be evaluated. The influence of compost on cropping systems largely has been investigated in grains and row crops or grasslands, with few studies focusing on its interaction with other practices over extended periods of application in perennial cropping systems like orchards (Hargreaves et al., 2008; Khalsa & Brown, 2017; Khalsa et al., 2022). Here, we investigated the interactions among long‐term compost application and irrigation techniques on N 2 O emissions in a California almond orchard.…”