Long term effects of manure, charcoal and mineral fertilization on crop production and fertility on a highly weathered Central Amazonian upland soil

Abstract

Application of organic fertilizers and charcoal increase nutrient stocks in the rooting zone of crops, reduce nutrient leaching and thus improve crop production on acid and highly weathered tropical soils. In a Weld trial near Manaus (Brazil) 15 diVerent amendment combinations based on equal amounts of carbon (C) applied through chicken manure (CM), compost, charcoal, and forest litter were tested during four cropping cycles with rice (Oryza sativa L.) and sorghum (Sorghum bicolor L.) in Wve replicates. CM amendments resulted in the highest (P < 0.05) cumulative crop yield (12.4 Mg ha ¡1 ) over four seasons. Most importantly, surface soil pH, phosphorus (P), calcium (Ca), and magnesium (Mg) were signiWcantly enhanced by CM. A single compost application produced fourfold more grain yield (P < 0.05) than plots mineral fertilized in split applications. Charcoal signiWcantly improved plant growth and doubled grain production if fertilized with NPK in comparison to the NPK-fertilizer without charcoal (P < 0.05). The higher yields caused a signiWcantly greater nutrient export in charcoal-amended Welds, but available nutrients did not decrease to the same extent as on just mineral fertilized plots. Exchangeable soil aluminum (Al) was further reduced if mineral fertilizer was applied with charcoal (from 4.7 to 0 mg kg ¡1 ). The resilience of soil organic matter (SOM) in charcoal amended plots (8 and 4% soil C loss, mineral fertilized or not fertilized, respectively) indicates the refractory nature of charcoal in comparison to SOM losses over 20 months in CM (27%), compost amended (27%), and control plots (25% loss).

Responses of absolute and specific soil enzyme activities to long term additions of organic and mineral fertilizer

“…Results from our previous long-term monitoring suggest that swine manure and mineral fertilizer may increase soil acidity (Dong et al, 2012), which is in agreement with Steiner et al (2007). The positive relationships between soil pH and TP contents in this study confirmed that calcium-magnesium phosphate fertilizers could neutralize acidity in acid soils (Fig.…”

“…Calcium-magnesium phosphate fertilizer can return alkaline substances to soils, resulting in increases in soil pH (Wu et al, 2008). Increases in soil pH because of swine manure applications may reflect the proton consuming ability of humic materials (Materechera and Mkhabela, 2002), and may have been due to the steady formation of organic material with functional groups during decomposition, such as carboxyl and phenolic groups, and by the low solubility of CaCO 3 (Steiner et al, 2007). However, the influence of mineral fertilizer on soil pH might be partially controlled by the soil characteristics and fertilizer properties.…”

Biochar affects soil organic matter cycling and microbial functions but does not alter microbial community structure in a paddy soil

“…Because BC is generally low in inorganic N, it is usually applied in conjunction with mineral fertilizer (Chen et al, 2013). In fact, the combination of BC and mineral fertilizers has been shown to synergistically affect crop yield and growth in field studies (Atkinson et al, 2010;Lehmann et al, 2003;Steiner et al, 2007). In addition to the possible effects of BC on microorganisms described above, the combination of fertilizer and BC may also affect microorganisms in field studies (via direct mineral nutrient input or indirect crop effects).…”

Assessment of Soil Health in Urban Agriculture: Soil Enzymes and Microbial Properties

“…Contrarily, the long-term application of inorganic fertilizer reduced the soil nutrients availability in the evaluated urban agricultural soils (Table 2). This may be due to the transformation of available forms of nutrients into unavailable forms by the soil acidity, and the poor nutrients retention corresponding to the low organic matter content in inorganic fertilizer applied soils [49]. The supplement of readily available nutrients (i.e., inorganic fertilizers) for a long-term tends to reduce the organic matter content in soil which causes in reduction of cation exchangeable sites.…”

“…The supplement of readily available nutrients (i.e., inorganic fertilizers) for a long-term tends to reduce the organic matter content in soil which causes in reduction of cation exchangeable sites. Therefore, soils ability to retain nutrients for plant growth get reduces and application of inorganic fertilizer in very short-terms is required to maintain the crop productivity [49]. Jiang et al [50] also reported a reduction of nutrient retention ability and crop production with respect to long-term application of inorganic fertilizers in winter wheat-maize rotation systems compare to the application of organic fertilizers.…”