Rock Phosphate as a Suitable Input for Canola

Rock phosphate is an environmentally sustainable, long lasting solution to the soil and plant health issues.

Fertoz Rock Phosphate provides a high quality source of plant needed phosphate with a guaranteeing analysis over 20% total phosphorus as P2O5 (7% available under NAC conditions) and also provides a valuable supply of calcium (30-60%) and silica (10-20%) which are beneficial and protective to canola crops.

Fertoz Rock Phosphate is sourced locally in Canada and the USA and contains minimal impurities.

Rock Phosphate Availability

Fertoz Rock Phosphate phosphorous availability is optimized in slightly acidic soils. In neutral to alkaline soils, Fertoz Rock Phosphate phosphorous availability is optimized through addition of elemental sulphur, humates, compost, manure, biologicals or in acidic fertilizer blends.

Some researchers have demonstrated rock phosphate is useful source for building residual phosphorus levels in the soil relative to synthetic fertilizers, promoting sustainable farming and future nutrient management planning (Sharma et al., 2010; Hongqing, et al., 2001; Choudhary et al., 1993). Unlike synthetic fertilizers, such as MAP, DAP or TSP,  phosphorous from rock phosphate can extend over many months or years (Partohardjono and Sri Adinignsih, 1991; Sharma, et al., 2010).  In addition, phosphate from rock phosphate seldom leaches or runs off the field into nearby lakes, streams and underground aquifers.

Conversely, synthetic phosphate fertilizers almost completely dissolve in moist soil solution (Lawton and Vomocil, 1954; Williams, 1969). Once in the soil, this phosphorus is either plant available, reacts with soil ions to form insoluble plant compounds (Barrow, 1983) and/or leaches into water sources.  

Agronomic Efficiency of Rock Phosphate in Canola

The geological source of rock phosphate is often used as to evaluate rock phosphate effectiveness. Sedimentary rock phosphate sources are considered more reactive and more soluble in soil solution than Igneous sources.

Canola is known to be very efficient utiliser of rock phosphate.  Rapeseed cultivars have been known to efficiently utilize both igneous (hard) and sedimentary (soft) rock phosphate (Bekele et al., 1983; Hoffland et al., 1989a; Bekele and Hofner, 1993; Smallberger et al., 2009, Montengro and Zapata, 2002).  Crops, like canola, can acidify the pH area surrounding the plant roots creating favourable environment for the dissolution of rock phosphate. This is accomplished through the exudation of organic acids; malic, oxalic, and citric acid, to create an acidified root environment (Brennan and Bolland, 2005; Mengel and Kirkby, 1987; Moorby et al., 1988; Hoffland et al., 1988, 1989a, 1989b). These results have been confirmed by multiple research trials in acidic and alkaline soils (Bekele and Hofner, 1993; Sharma, et al., 2010, Jones, 1998; Chien, 2003; Chien et al., 2003; Habib et al., 1999; Pillai, et al., 2014).

Rock Phosphate versus Synthetic Fertilizers (MAP, DAP or TSP)

Many researchers have demonstrated that canola (or other crops) fertilized with rock phosphate will at times be equal or out yield canola (or other crops) fertilized with synthetic fertilizers, such as TSP and DAP on acidic soils (Beckle and Hofner, 1993; Hongqing, et al., 2001; Smallberger et al., 2009; Choudhary, et al., 1993; Montenegro and Zapata, 2002) or with amendments on neutral or higher pH soils (Sharma, et al., 2010). 

Other researchers have demonstrated that a combination of synthetic phosphate fertilizers and rock phosphate have out yielded synthetic commercial fertilizer applications on their own, which is not that unexpected as rock phosphate extends the phosphate availability window while synthetic water soluble fertilizer provides a strong initial plant boost (Bekele and Hofner, 1993; Habib et al., 1999; Choudhary, et al., 1993; Pillai, et al., 2014).

Disease Protection

The persistent, soil borne pathogen Plasmodio-phora brassicae causing clubroot has been an increasing threat to canola in Western Canada. The issue is further exacerbated by minimal rotations. Clubroot causes premature death of the plant resulting in substantial yield losses, equating to over 50% yield loss in severe cases. Once manifested, clubroot cannot be removed from the field and therefore prevention measures are important.

Soil amendments such as lime, calcium carbonate, calcium cyan amide and calcium rich organic matter have been studied as management strategies and have showed favorable disease management potential (Canola Council of Canada, 2019; Graham et al., 2016). Soil calcium ion content has been known to reduce clubroot severity in host crops (Donald et al., 2004; Myers and Campbell, 1985; Niwa et al., 2007; Tremblay et al., 2005). In a study by Graham et al., 2016, soil calcium levels correlated to reduced clubroot severity and significantly higher yields.

Fertoz Rock Phosphate contains a healthy dose of calcium (30-60%) and silica (10 to 20%) which are known to promote crop vigour, improving crop defense mechanisms.

Image from The Canola Council of Canada Website: https://www.canolacouncil.org/canola-encyclopedia/diseases/clubroot/about-clubroot/

References

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