Phosphate Balance in Cropland

Home Based Recycling Business

Make Money in the Recycling Business

Get Instant Access

The national phosphorus balance varies significantly from one country to another, due to differences in the use of mineral fertilizers and manure, and differences in animal husbandry practices. Broadly speaking, in developing countries, soils tend to be deficient in phosphorus, while in developed countries the phosphorus content of the soils is adequate or even excessive. Taking into account applications of mineral fertilizers and manure, the balance for some West European countries is positive, particularly in the Netherlands where it exceeds 39 kgPha-1 each year. For the majority of Western European countries, the phosphorus balance ranges from 8.7 to 17.5 kg P ha- annually. China, one of the largest agricultural systems in transition, also achieved a positive balance around 1980 at the national level, in parallel with increasing application of synthetic fertilizers. In 2000, the national surplus of phosphorus in Chinese soils was estimated at an average of 16 kg P ha- .

The world phosphorus budget for cropland is summarized in Table 3. To balance the phosphorus budget for the world's cropland, two natural inflows ofphosphorus to croplands should be taken into account. Based on the ratio of cropland area to world total land areas, weathering and atmospheric deposition contribute 2.0 MMT Pyr- as inputs to world croplands. Although the magnitudes of recycling of animal wastes and soil erosion need further verification, the budget provides a comprehensive overview on the global phosphorus flows associated with the farming sector, which is the most intensive and complicated subsystem of the anthropogenic phosphorus cycle.

Table 3 Phosphorus budget for the world's cropland in recent year (2004)

Flows

Annual fluxes (MMT P)

Inputs

22.0

Weathering

1.6

Atmospheric deposition

0.4

Synthetic fertilizers

13.8

Organic recycling

6.2

Crop residues

2.2

Animal wastes

2.5

Human wastes

1.5

Removals

12.7

Crops

8.2

Crop residues

4.5

Losses

19.8

Erosion

19.3

Runoff

0.5

Balance

-10.5

Input shares

Fertilizer application

69%

Organic recycling

31%

Uptake efficiency

64%

Was this article helpful?

0 0
Trash Cash Machine

Trash Cash Machine

How recyclable trash can save the world and bank us huge profits! Get All The Support And Guidance You Need To Be A Success At Recycling! This Book Is One Of The Most Valuable Resources In The World When It Comes To How To Make Profits With Trash!

Get My Free Ebook


Post a comment