Long‐term effects of manure and fertilization on soil organic matter and quality parameters of a calcareous soil in NW China

Abstract

Long‐term applications of inorganic fertilizers and farmyard manure influence organic matter as well as other soil‐quality parameters, but the magnitude of change depends on soil‐climatic conditions. Effects of 22 annual applications (1982–2003) of N, P, and K inorganic fertilizers and farmyard manure (M) on total organic carbon (TOC) and nitrogen (TON), light‐fraction organic C (LFOC) and N (LFON), microbial‐biomass C (MB‐C) and N (MB‐N), total and extractable P, total and exchangeable K, and pH in 0–20 cm soil, nitrate‐N (NO$ _3^- $‐N) in 0–210 cm soil, and N, P, and K balance sheets were determined using a field experiment established in 1982 on a calcareous desert soil (Orthic Anthrosol) at Zhangye, Gansu, China. A rotation of irrigated wheat (Triticum aestivum L.)‐wheat‐corn (Zea mays L.) was used to compare the control, N, NP, NPK, M, MN, MNP, and MNPK treatments. Annual additions of inorganic fertilizers for 22 y increased mass of LFON, MB‐N, total P, extractable P, and exchangeable K in topsoil. This effect was generally enhanced with manure application. Application of manure also increased mass of TOC and MB‐C in soil, and tended to increase LFOC, TON, and MB‐N. There was no noticeable effect of fertilizer and manure application on soil pH. There was a close relationship between some soil‐quality parameters and the amount of C or N in straw that was returned to the soil. The N fertilizer alone resulted in accumulation of large amounts of NO$ _3^- $‐N at the 0–210 cm soil depth, accounting for 6% of the total applied N, but had the lowest recovery of applied N in the crop (34%). Manure alone resulted in higher NO$ _3^- $‐N in the soil profile compared with the control, and the MN treatment had the highest amount of NO$ _3^- $‐N in the soil profile. Application of N in combination with P and/or K fertilizers in both manured and unmanured treatments usually reduced NO$ _3^- $‐N accumulation in the soil profile compared with N alone and increased the N recovery in the crop as much as 66%. The N that was unaccounted for, as a percentage of applied N, was highest in the N‐alone treatment (60%) and lowest in the NPK treatment (30%). In the manure + chemical fertilizer treatments, the unaccounted N ranged from 35% to 43%. Long‐term P fertilization resulted in accumulation of extractable P in the surface soil. Compared to the control, the amount of P in soil‐plant system was surplus in plots that received P as fertilizer and/or manure, and the unaccounted P as percentage of applied P ranged from 64% to 80%. In the no‐manure plots, the unaccounted P decreased from 72% in NP to 64% in NPK treatment from increased P uptake due to balanced fertilization. Compared to the control, the amount of K in soil‐plant system was deficit in NPK treatment, i.e., the recovery of K in soil + plant was more than the amount of applied K. In manure treatments, the recovery of applied K in crop increased from 26% in M to 61% in MNPK treatment, but the unaccounted K decreased from 72% in M to 37% in MNPK treatment. The findings indicated that integrated application of N, P, and K fertilizers and manure is an important strategy to maintain or increase soil organic C and N, improve soil fertility, maintain nutrients balance, and minimize damage to the environment, while also improving crop yield.

Short-term residual effects of various amendments on organic C and N, and available nutrients in soil under organic crop production

“…Earlier research in China has shown substantial increase in extractable P and total P in soil with long-term annual applications of FYM [5]. In our study, extractable P in the surface soil also increased considerably with compost even after three annual applications.…”

“…Fertilization with organic amendments, such as compost manure/farm yard manure (FYM), alfalfa pellets/powder, distiller grain and thin stillage can have both direct (e.g., enhancing organic C in soil) and indirect (e.g., providing available nutrients after decomposition/mineralization) benefits on soil physical, chemical and biological properties, and crop yields [1][2][3][4][5][6][7][8][9]. Inorganic amendments and microbial inoculants, such as wood ash, rock phosphate, Penicillium bilaiae, MykePro, gypsum and elemental S, have been investigated for their potential as organic fertilizers in many studies, but their effectiveness to increase the availability of P or S in soil, and subsequently improve crop yield varies with nutrient source/type, severity of P, S and other nutrients deficiency in soil, soil type and climatic conditions [10][11][12][13].…”

“…Thus, organic amendments (because of both direct and indirect C input) can have much greater residual benefits in improving soil organic matter/quality and fertility compared to inorganic amendments which contribute only indirectly to C input in soil [3][4][5][6][17][18][19]. However, the effects of various amendments on soil properties vary with soil-climatic conditions.…”

Effects of fertilization regimes on tea yields, soil fertility, and soil microbial diversity

“…Soil pH ranging from 5.40 to 5.68 was not significantly different across all treatments, indicating that there was no noticeable effect of fertilizers on soil pH after 5 yr of continuous annual fertilizer applications. Yang et al (2007) and Gu et al (2009) also reported that inorganic fertilizer and organic amendment had no effect on soil pH after 22 yr of continuous annual fertilizer applications. However, Shen et al (2010) and Hu et al (2011) showed that inorganic and organic fertilization significantly decreased soil pH after long-term fertilizer applications.…”

“…Many studies have focused on fertilization regimes on soil fertility Liu et al, 2010), crop yields (Venkatesan et al, 2004;Zhu et al, 2007) and microbial communities (He et al, 2008;Shen et al, 2010), but, up to now, the results of these reports are still not unanimous, and even conflicted. Moreover, most studies were concerned about the soils for growing food crops, like rice (Wu et al, 2011), wheat (Shen et al, 2010), maize or their combination for rotation (Kumar and Yadav, 2001;Yang et al, 2007;Hu et al, 2011), while few about the soils for planting tea (Venkatesan et al, 2004). Hence, it is necessary to examine the effects of fertilization regimes on tea yields, soil fertility, and microbial communities.…”