Elsevier

Field Crops Research

Volume 169, December 2014, Pages 116-122
Field Crops Research

Long-term effects of potassium fertilization and straw return on soil potassium levels and crop yields in north-central China

https://doi.org/10.1016/j.fcr.2014.09.017Get rights and content

Highlights

  • K fertilization and/or straw return alleviated soil K depletion.

  • Fertilization strategies influenced soil K levels mainly in the 0–30 cm depth.

  • Straw return increased soil organic C sequestration in the top 40 cm.

  • K fertilization and/or straw return increased crop yield.

  • K fertilizer should be prior applied in maize to enhance yield and K efficiency.

Abstract

Understanding the changes in soil potassium (K) and crop yield under K fertilization and straw return is important for proper K fertilizer management. A field experiment involving a wheat (Triticum aestivum L.)–maize (Zea mays L.) rotation was conducted to study the effects of long-term (20-year) K fertilization and straw return on soil K and crop yield in north-central China. Fertilization treatments included: nitrogen and phosphorus fertilizers (NP), NP plus wheat straw (NPS), NP and K fertilizers (NPK), and NPK plus wheat straw (NPKS). Annual soil K budget increased with increasing K inputs (including fertilizer K and straw K) in the order of NP < NPS < NPK < NPKS, and further increased after maize straw returned since 2008. The NP and NPS treatments decreased soil available K and slowly available K below the initial levels, K fertilization and/or straw return increased available K and slowly available K in the top 30 cm soil over the NP treatment. Fertilization did not significantly alter total K in the 0–100 cm depths, but in the 0–10 cm soil layer, the NP, NPS, and NPK treatments decreased total K by 4.3%, 3.4%, and 0.4% than the initial concentration, respectively. Compared with the NP treatment, K fertilization and/or straw return increased crop yields in most cases, and the effect of K inputs on yield increase was greater for maize than wheat. Additionally, increased straw return enhanced soil organic carbon (SOC) beyond the NP treatment, and SOC decreased with depths between 0 and 40 cm soil; however, fertilization did not change SOC below 40 cm. In conclusion, K fertilization and/or straw return alleviated soil K depletion and increased soil K fertility; crop yields increased with increasing K inputs, and yield response of maize to K fertilization was greater than wheat.

Introduction

Potassium (K) is an essential nutrient and is involved in many important physiological processes in plants; it can improve crop quality and the ability of plants to survive adverse conditions (Marschner, 1995, Pettigrew, 2008). Sufficient K supply in soil helps to ensure high crop yield (Dong et al., 2010, Zhang et al., 2011). K deficiency is a world-wide problem, and the K levels in agricultural soils is decreasing across the globe (Fagerberg et al., 1996, Dobermann et al., 1998, Wijnhoud et al., 2003, Malo et al., 2005). In China, the majority of K fertilizer applied is imported, and soil K deficiency is recognized as one of the limiting factors for crop production (Zhang et al., 2008). The imbalanced fertilizer use in China led to a surplus or balanced situation for soil nitrogen (N) and phosphorus (P) but a serious depletion of K (Lin et al., 2006, Wang et al., 2008). Extending balance fertilization technology has enhanced K fertilizer input in crop production, but the increasing price of K fertilizer has increased agricultural production costs (Wang, 2012). Therefore, efficient use of K fertilizer is crucial for this resource limited nutrient.

Crop straw is an important organic fertilizer resource, especially for Li and Jin (2011) reported that China produced 8.1 × 108 t of crop straw in 2008, and this supplied 1.2 × 107 t of K2O. Therefore, straw retention in fields can return a considerable amount of plant K to the soil. In addition, straw retention could also decrease mineral N fertilizer losses by causing N immobilization in the short term, and increase carbon (C) sequestration in soil and enhance soil quality (Yadvinder-Singh et al., 2004, Plante et al., 2006, Liu et al., 2011). Recently, both wheat and maize straws return was widespread in winter wheat–summer maize rotation system in north-central China because the use of straw returning machine was increased in response to a ban by the Chinese government on field burning of crop straws. However, straw decomposition and nutrient release from straw were slow in the field, and the effects of straw return on crop yield, soil fertility and quality were not obviously shown in short term (Brunetto et al., 2011, Partey et al., 2011, Wang et al., 2010). Long-term field experiment could demonstrate the effects of different nutrient management strategies on crop yield, soil nutrient dynamics, and soil quality (Gong et al., 2009, Malhi et al., 2011, Liang et al., 2012). Several long-term experiments on fertilization and straw return treatments have been established in northern China, but these studies on changes in soil quality and nutrients mainly focused on topsoil, while few have focused on the deeper layers (Cao et al., 2008, Liu et al., 2010, Zhang et al., 2010, Zhang et al., 2011). Breulmann et al. (2012) indicated that research on the deeper soil layers could provide more information about soil nutrient properties. The objective of this study was to investigate the changes in soil K levels and crop yields under long-term K fertilization and straw return in north-central China.

Section snippets

Experimental site

Field experiment was conducted in October 1992 in fluvo-aquic soil (Calcaric Cambisols, FAO) at Malan farm (37°55′ N, 115°13′ E), Hebei province, north-central China. This region has a warm temperate, sub-humid continental monsoon climate. The annual mean temperature and precipitation are 12.5°C and 490 mm, respectively, and 70–80% of the annual precipitation occurs during the summer maize-growing season. The soil tested has a light loam texture with following properties in top 20 cm soils at the

Crop K uptake and soil K balance

Fertilization significantly affected wheat and maize K uptakes; however, experimental stage (five years as an experimental stage) only influenced maize K uptake (Table 1). Among the four treatments, annual wheat K uptake showed significant differences as: NP < NPS  NPK  NPKS in 1993–1997 and 1998–2002, NP < NPS < NPK = NPKS in 2003–2007 and 2008–2012. Annual maize K uptake in the same treatment increased with experimental time. The K uptake by maize in four treatments showed consistent trends as: NP < NPS < 

Crop K uptake and soil K balance

The level of soil K supply significantly affected crop K uptake (Dobermann et al., 1998, Mallarino et al., 2012). In this study, annual wheat and maize K uptakes all increased with increasing K inputs (including fertilizer K and straw K) in the sequence of NP < NPS </≤ NPK  NPKS. The NP, NPS, and NPK treatments resulted in negative annual soil K budgets due to total K inputs were lower than total K removal by crops from 1993 to 2007. Niu et al., 2011, Niu et al., 2013 also reported that the

Conclusions

Our study confirmed that K fertilization and/or straw return alleviated soil K depletion and enhanced soil K fertility, and high rate of K inputs enhanced their effects. Different fertilization strategies influenced soil available K and slowly available K mainly in the top 30 cm soil, and total K changed only in the 0–10 cm soil compared with the initial level. Straw return enhanced SOC, however, fertilization affected SOC mainly in the top 40 cm. K fertilization and/or straw return increased crop

Acknowledgements

This project was supported by the National Basic Research Program of China (973 Program) (2013CB127404 and 2013CB127405), the National Natural Science Foundation of China (31272243 and 31272245) and the International Plant Nutrition Institute (IPNI).

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