Monday, July 20, 2015

Industrial Livestock Production and Soil Phosphorus Imbalance (Includes an example from a developing country)

Profitability is a major concern of every industry. Livestock industry is no exception to this rule. Regional concentration of livestock is a consequence of the industry's drive to become more profitable. For instance, only eight states deliver more than 70% of the USA broiler production, which signifies the degree of broiler concentration in a country constituted by 50 states. Only one state, namely Georgia, produces 15% of the USA broilers. A similar concentration is observed in another major broiler producing country: Bolu province of Turkey delivers 10% of the national broiler production (Güngör, 2013).

When humans or animals are concentrated regionally, inadvertent environmental impacts are bound to occur. Let us take a look one of the agri-environmental impacts of livestock concentration:

Feed demand of large numbers of livestock exceed local feed supply --> Feed is imported --> Livestock excrete large amounts of manure --> Excess manure phosphorus creates a regional phosphorus imbalance for the agricultural soil.

What is "Phosphorus (Im)Balance"?

Phosphorus balance is essentially a simple mass balance equation that includes phosphorus input and output of the agricultural top soil
Phosphorus balance = Input (e.g., manure, fertilizer) - Output (e.g., harvested crop)/ Agricultural Land
Input, output, and agricultural land data are typically obtained from regional or national organizations that keep statistical records. 
Organization of Economical Cooperation and Development (OECD) uses phosphorus balance as an agri-environmental indicator and regularly publishes the national balances of its member countries which include USA and Turkey.

You can see the national phosphorus balances of OECD member countries for the periods of 1990-1992 and 2002-2004 from here.
So, what does "phosphorus imbalance" indicate?
If agricultural soil has positive imbalance,
  • Phosphorus may become a limiting nutrient, crops may suffer fromphosphorus stress, and subsequently crop yields may decrease.
If agricultural soil has negative imbalance,
  • Phosphorus may be applied in excess of crop needs, accumulate in soil, and cause eutrophication if transported to surface waters
Hence, positive and negative imbalance indicate risks that can threaten food security and aquatic ecosystem quality, respectively, if they are materialized.
Scale does matter: national versus regional balances
Spatial distribution of phosphorus imbalance can be resembled to wealth distributionSome have a lot whereas some have little. Therefore, national phosphorus balances can mask regional phosphorus imbalances. Policymakers can look at the national balance values and can easily say: 
"Phosphorus balance of our country looks not too bad..."
Such an assessment can easily translate into inaction and exacerbate the situation in regions with significant and persistent phosphorus imbalance problem. 
Influence of poultry industry on regional phosphorus imbalance: a Turkish case
Turkey is the sixth leading poultry meat exporter in the world. Between 1990 and 2007, annual broiler meat production in Turkey increased almost seven-fold, exceeding one million metric tons (Güngör, 2013). The country is also an OECD member that has a moderate positive annual phosphorus imbalance hovering around 5 kg P/ha. 
Out of curiosity, I applied the OECD phosphorus balance method on Bolu province which is a preferred region of the poultry industry. The province has experienced a tremendous growth in terms of broiler production in the past few decades. To my knowledge, this is the first study of its kind precipitated in Turkey. 
I found that phosphorus imbalance of Bolu tripled the national imbalance (please see years 2003 & 2004 in the figure below) indicating a clear mismanagement of a valuable and non-renewable agricultural nutrient and associated environmental pollution risk. The percentages shown over each bar in the figure are the phosphorus use efficiency. The phosphorus use efficiency figures of Bolu indicates that the province only convert 1/3-1/4 of the available phosphorus into crops 
I must also highlight the fact that Turkey is a country that (a) lacks significant phosphate rock reserves to be used in the fertilizer production like many other countries in the world, (b) its farmers almost constantly complain about the high fertilizer prices, (c) has eutrophic lakes. 
Therefore, when you hear people talk about agricultural or environmental sustainability, please remember this point and be aware that we need to be good stewards of our non-renewable resources, including but not limited to, phosphorus.
Figure Reference: Güngör (2013)

Saturday, July 11, 2015

Broiler Litter Select Characteristics (My Case Study in Turkey)/ Et Tavuğu Gübresinin Bazı Özellikleri (Bolu Saha Çalışmam)

Broiler litter samples were collected and analyzed in the scope of my intramurally-funded research project in Turkey. The study area was Bolu province. Rice hulls are typically used as bedding in the broiler houses.

Fresh samples: were collected from the broiler house floor upon the completion of a production cycle which is typically between 40-50 days.

Stockpiled samples: were obtained from the little piles where the litter is stored before they are applied on cropland following crop harvest, which is typically in late summer in the region.

If the tables are interesting for you and you want to use them, please cite the following peer-reviewed article of mine. You can also use the link to access the full manuscript.


Physicochemical characteristics of the fresh and stockpiled litter.[a]
Litter
Type
Sample
Size
Dry 
Matter
%
Organic Matter
%
pH[b]
EC[b]
mS cm-1
TKN
%
TP[c]
%
N:P[c]
Fresh
 22
72.7 a
±11.8
60.9 a
±6.1
8.4 a
±0.8
8.36 a
±0.80
3.47 a
±0.49
1.36 a
±0.31
2.64 a
±0.67
Stockpiled
28
64.2 b
±6.7
50.4 b
±11.7
8.4 a
±1.0
8.37 a
±1.00
2.62 b
±1.14
1.71 b
±0.50
1.76 b
±0.55
[a]   Values are means ± standard deviations. Means in the same column followed by different letters are significantly different (p < 0.05).
    No inter-column statistical comparison was made. TKN = total Kjeldahl nitrogen (dry basis), TP = total phosphorus (dry basis), EC = electrical conductivity, and N:P = ratio of total Kjeldahl nitrogen to total phosphorus (g N g-1 P).
[b]   pH and EC were determined in 1:2 (v/v) suspensions.
[c]   Fresh and stockpiled sample sizes were 21 and 14, respectively.

Major metals in the fresh and stockpiled broiler litter.[a]
Litter
Type
Sample
Size
Na
%
K
%
Ca
%
Mg
%
Mn
mg kg-1 
Fe[b]
mg kg-1
Cu
mg kg-1
Zn
mg kg-1
Ba
mg kg-1
Fresh
21
0.36 a
±0.05
3.86 a
±0.54
2.59 a
±0.78
0.52 a
±0.11
571 a
±114
1432 a
±1478
90.7 a
±20.9
594 a
±105
18.2 a
±6.7
Stockpiled
14
0.36 a
±0.12
4.14 a
±0.82
3.55 b
±1.31
0.68 b
±0.22
763 b
±235
1574 a
±728
104.4 a
±37.1
725 a
±251
23.9 a
±9.1
[a]   Values are means ± standard deviations. Means in the same column followed by different letters are significantly different (p < 0.05).
No inter-column statistical comparison was made.
[b]  Fe was not detected in one stockpiled sample and was <581 mg kg-1 in three fresh and one stockpiled sample.

 

Turkish version of this post is given below (Türkçe):

    Abant İzzet Baysal Üniversitesi Çevre Mühendisliği'nde öğretim üyesi iken yürüttüğüm bilimsel araştırma projesi (BAP) kapsamında Bolu ilinde üretilen et tavuğu (broyler) gübresi örnekleri toplanarak analiz edilmiştir. Tavuk kümeslerinde altlık olarak genelde çeltik kavuzu kullanılmaktadır.

Taze örnekler: 40-50 gün kadar süren besleme dönemi tamamlandıktan ve tavuklar kesime götürüldükten hemen sonra kümeslerin tabanlarından toplanmıştır.

Yığın örnekleri: kümeslerin bulunduğu bölgelerin yakınındaki üstü açık gübre yığınlarından alınan örneklerdir. Gübre hasat ardından yaz sonunda tarlalara uygulanmaktadır. 

Aşağıda verdiğim tablolara ilginizi çektiyse ve bunlardaki verileri herhangi bir biçimde kullanmak istiyorsanız, lütfen aşağıdaki hakemli dergide İngilizce olarak yayınlanmış makaleme atıf yapınız: 


Et tavuğu gübresinin fizikokimyasal özellikleri.[a]
Gübre Türü
Örnek Sayısı
Kuru Madde
%
Organik Madde
%
pH[b]
EC[b]
mS cm-1
TKN
%
TP[c]
%
N:P[c]
Taze
22
72.7 a
±11.8
60.9 a
±6.1
8.4 a
±0.8
8.36 a
±0.80
3.47 a
±0.49
1.36 a
±0.31
2.64 a
±0.67
Yığın
28
64.2 b
±6.7
50.4 b
±11.7
8.4 a
±1.0
8.37 a
±1.00
2.62 b
±1.14
1.71 b
±0.50
1.76 b
±0.55
[a]   Değerler ortalama ± standart sapma olarak verilmiştir. Aynı sütundaki farklı harfler değerlerin birbirinden % 95 istatistiksel olasılıkla farklı olduğunu göstermektedir.
   Sütunlar arası bir istatistiksel inceleme yapılmamıştır. TKN = toplam Kjeldahl azotu (katı bazda), TP = toplam fosfor (katı bazda), EC = elektrik iletkenliği, and N:P =  toplam Kjeldahl azotu toplam fosfor kütlesel (g N g-1 P). Gübrenin nitrit, nitrat içeriği epeyce düşük olduğundan TKN toplam azota eşitmiş gibi kabul edilebilir.
[b]  pH and EC hacmen 1:2 süspansiyonlar içinde ölçülmüştür. 
[c]  Taze ve yığın örnek sayıları sırasıyla 21 ve 14'tür.

Taze ve yığında bekletilmiş et tavuğu gübresindeki ana metaller.[a]
Gübre 
Türü
Örnek Sayısı
Na
%
K
%
Ca
%
Mg
%
Mn
mg kg-1 
Fe[b]
mg kg-1
Cu
mg kg-1
Zn
mg kg-1
Ba
mg kg-1
Taze
21
0.36 a
±0.05
3.86 a
±0.54
2.59 a
±0.78
0.52 a
±0.11
571 a
±114
1432 a
±1478
90.7 a
±20.9
594 a
±105
18.2 a
±6.7
Yığın
14
0.36 a
±0.12
4.14 a
±0.82
3.55 b
±1.31
0.68 b
±0.22
763 b
±235
1574 a
±728
104.4 a
±37.1
725 a
±251
23.9 a
±9.1
[a]   Değerler ortalama ± standart sapma olarak verilmiştir. Aynı sütundaki farklı harfler değerlerin birbirinden % 95 istatistiksel olasılıkla farklı olduğunu göstermektedir.
Sütunlar arası bir istatistiksel inceleme yapılmamıştır. 
[b]  Fe bir örnekte ölçülebilecek değerinde altında kalmış, üç taze ve bir yığında bekletilmiş örnekte ise 581 mg kg-1 den düşük bulunmuştur.