MK. Manajemen Kesuburan Tanah BEST MANAGEMENT PRACTICES Oleh : Prof.Dr.Ir.Soemarno,M.S

MK.Manajemen Kesuburan Tanah

BEST MANAGEMENT PRACTICES

Oleh:Prof.Dr.Ir.Soemarno,M.S.

FP-UB, Okt 2013

BMPsBEST

MANAGHEMENT PRACTICES

NITROGEN BMPs FOR SMALL FARMS

"Nitrogen best management practices for small farms in the Pacific Northwest." Diunduh dari: http://www.uiweb.uidaho.edu/wq/wqbr/wqbr20.html ……….. 6/10/2012

Kebutuhan N manusiaNitrogen (N) is an element essential for all

plant and animal life.

Humans have a nutritional requirement of 55 pounds of protein per year. Nitrogen is a

component of protein. There are 8.8 pounds of nitrogen in 55 pounds of protein.

In the USA a typical person obtains half their protein from animal sources, and the other half

from vegetable matter.



EFISIENSI PENGGUNAAN N

Kebutuhan manusia secara teoritis hanya 8.8 lbs N protein setahun, namun inefisiensi ekosistem harus

diperhitungkan. Sehingga diperlukan lebih dari 8.8 lbs N , karena tumbuhan dan hewan tidak efisien dalam

menangkap N dari ekosistem.

Tanaman dianggap 50% efisien – sehingga hanya mampu mengubah sekitar 50% N menjadi protein.

Sedangkan hewan lebih kurang efisien, hanya sekitar 15% N yang dikonversi menjadi protein.

Kalau diasumsikan manusia mendapatkan suplai protein nabati sekitar 50%, maka ia memerlukan 38 lbs N per

tahun untuk memenuhi kebutuhan proteinnya; bukan 8.8 lbs N.



SIKLUS NITROGENThis diagram represents a simplified nitrogen cycle.

Agriculture affects both N additions and subtractions to the soil. Additions include N fertilizers, crop residues, N fixation

by legumes, and manures. Subtractions attributed to agriculture include crop removal (harvesting), plant uptake,

and N leaching. Plants can use two forms of N -- ammonium and nitrate.

Nitrate is the plant available form of N that can leak or leach from the system and have a detrimental effect on the

environment. Another important aspect of the N cycle is the process called mineralization. In this process organic matter (OM) breaks down and forms plant available ammonium and

eventually nitrate.

Crops residues, animal and plant manures, and composts when added to the soil become part of the soil OM which

when mineralized will form ammonium and nitrate.



KEHILANGAN NITROGEN

Anytime we have leaks in the nitrogen cycle there are some environmental concerns. The two biggest

problems which can impact water quality are leaching and erosion. Nitrates are mobile in soils

and can leach into our groundwater supplies. On the other hand soil erosion has a negative

impact on surface water quality -- our streams, rivers, and lakes. Organic matter is concentrated

on the soil surface.

Consequently, if soil erosion occurs, this nitrogen containing organic matter washes off the land into

our surface water sources.



SUMBER Nada beberapa sumber N yang digunaklan dalam ekosistem

pertanian. Common N sources include the decomposition of soil organic

matter, commercial N fertilizers, animal manures, plant residues,

and composts. The decomposition of soil organic matter -- called

mineralization is a natural process that occurs in all soils.

Dalam ekosistem non-pertanian, mineralisasi BOT menjadi sumber

utama N bagi tanaman.

N dalam Pertanian

N adalah hara esensial makro yang dibutuhkan

tanaman. Tanaman menyerap N lebih

banyak dibandingkan dnegan unsur lainnya.

Plants contain anywhere from 1 to 5% nitrogen on a

dry weight basis. The importance of nitrogen to all agricultural systems is

unquestionable.



Nitrates dalam Groundwater

Nitrates dalam tanah sangat mobil. Berlebihannya air ke lahan dapat mencuci nitrat ke luar tanah, dan

mencemari groundwater.

Baku mutu air minum maksimum mengandung 10 ppm N-nitrate.

Recent surveys have shown that about 2% of the rural wells in the PNW

currently exceed this 10 ppm nitrate-nitrogen drinking water standard.

Bentuk N

Semua sumber N yang diberikan ke tanah pada akhirnya menghasilkan amonium dan nitrat.

Nitrate paling panyak diserap tanaman dalam

ekosistem pertanian.

Nitrate is nitrate -- it does not matter to the plant whether it

came from commercial nitrogen fertilizer or if it

mineralized from a compost pile.



N-MANAJEMEN

When we talk about proper nitrogen management to prevent water

pollution there are two key concepts one needs to become familiar with.

Konsep pertama adalah efisiensi nitrogen atau disingkat NUE.

Konsep ke dua adalah best- management-practices, disingkat

BMP.

N-Manajemen

Proper nitrogen management on small farms is important for

three reasons. Pengelolaan N yang tepat

dapat memperbaiki kualitas tanaman.

Pengelolaan N yang tepat sangat menguntungkan. Pengelolaan N yang tepat

dapat melindungi lingkungan.



KONSEP NITROGEN Efisiensi Nitrogen (NUE) didefinisikan sebagai

persentase N-tersedia dalam tanah yang diserap tanaman, nilainya berkisar 0 - 100 %.

Ideally, we would like to see an NUE value of 100%. The greater the NUE value -- the less plant

available nitrogen is left in the soil.

Plant available nitrogen left in the soil could leach and contaminate our groundwater supplies.

Nilai NUE yang tinggi sangat penting karena -- (1) perlindungan lingkungan, dan (2) profitabilitas

usahatani.



KONSEP NITROGEN Apakah N dalam NUE?

The nitrogen is plant-available nitrogen in the soil. It includes both nitrate and ammonium.

This would be the sum total of ammonium and nitrate that got into the soil by the following

means:

1. Ammonium Dan nitrate dimineralisasi dari BOT, 2. Nitrogen ditambahkan sebagai pupuk N,3. Residu ammonium dan nitrates yang tertinggal

dalam tanah yang tidak diserap oleh tanaman yang terakhir.



KONSEP NITROGEN

Across the country, nitrogen use efficiency averages about 50% for most crops. Intensive

management using best management practices can result in NUE values approaching 70% in

production agriculture.

On the other hand, poor or careless management often results in NUE values less

than 30%. Small farms lend themselves to intensive management.

Consequently, a NUE goal of 75% is realistic when nitrogen best management practices are

employed.



KONSEP NITROGEN

APA artinya efisiensi nitrogen (NUE) 45%?

It simply means that 45% of the plant-available nitrogen -- ammonium and nitrate -- in the soil was taken up by the

plant. What happened to the other nitrogen that constitutes the

55% not taken up by plants?

Well, a portion of it remained in the soil, a portion may have leached, and a portion was utilized by soil microbes

or taken up by weeds.



KONSEP NITROGEN

The other concept of importance is best management practice, or BMP. Best management practices can be defined as implemented

strategies which eliminate or minimize non-point source agricultural pollution. There has been extensive research to design best

management practices for nitrogen management.

BMP dirancang sesuai dengan kondisi dan karakteristik ekosistem pertanian.

Penerapan BMP diharapkan dapat melindungi lingkungan tanpa mengorbankan profitabilitas usaha pertanian.



Ada tujuh BMP Nitrogen yang harus diadopsi oleh usahatani sekala kecil.

BMP Nitrogen yang pertama adalah aplikasi dosis pupuk optimum pada setiap bidang lahan usaha.

To do this correctly, you must consider the following: soil testing, setting realistic yield goals for the crops in each field, providing

nitrogen credits from soil organic matter, providing nitrogen credits for manures and legumes incorporated into your fields, and you

need to consider the overall vulnerability of groundwater to contamination.

Semakin besar ancaman yang ada – semakin penting segera menerapkan BMP.



You must test your soil to determine its organic matter content and the amount of plant-

available nitrogen -- ammonium and nitrate present. This is a necessary best management

practice.

Dosis pupuk Nitrogen harus didasarkan pada hasil analiosis sampel tanah dan target hasil

tanaman yang realistis.

A realistic yield goal will allow accurate determination of optimum nitrogen rates for

crop production. Yield goals that are too low will under estimate

nitrogen needs and result in both reduced yields and profits.



Pengambilan sampel tanah dari lahan usaha harus mengukuti prosedur baku yang berlaku.

Soil samples for OM content should be taken to a depth of 12 inches. For ammonium and nitrate the soil sample should be taken to the effective rooting depth of the crop that will be planted. Your local

extension office can help here also. The soil samples should be taken 3 to 4 weeks prior to planting. The

soil sample should be analyzed by a reputable laboratory. The numbers provided by the soil testing laboratory can be interpreted

by your county agent.

Dosis pupuk N berdasarkan hasil analisis tanah, sesuai dengan rekomendasi pemupukan bagi tanaman yang ditanam.



TARGET HASIL TANAMAN

Yield goals that are too high will over estimate nitrogen needs. This will result in excess plant available nitrogen in

the soil profile. This increases the potential for groundwater contamination with nitrates.

In addition to accounting for the nitrogen in a soil test one must consider giving credit to nitrogen obtained from

other sources. You should take into account the nitrogen in soil organic

matter, legumes, animal manures, composts plus other soil additives, and sludge.



KREDIT NITROGEN

Nitrogen credits should be given for the amount of organic matter in the soil.

BOT mengalami dekomposisi dengan kecepatan sekitar 1.5% per tahun.

Dekomposisi BOT akan menghasilkan -- ammonium dan nitrate – yang tersedia bagi tanaman.

Secara umum, untuk tanaman yang ditanam pada tanah-tanah yang mengandung BOT 1% , harus

dikredit dengan 15 pound N-tersedia. Sekitar 15 pound N-tersedia harus dikredit untuk

setiap satu persen BOT dalam tanah.



Tabel ini menunjukkan kredit N-tersedia untuk

lahan-lahan yang mengandung BOT 1 -

10%.

Konstante sebesar 15 pound dibagi persen

BOT dapat digunakan untuk menduga jumlah BOT yang mengalami

dekomposisi menjadi N-tersedia dalam tanah.



KREDIT NITROGEN

Kredit Nitrogen juga harus diberikan kalau legum ditanam pada musim tanam yang lalu.

Residue from these legumes will provide some nitrogen for the next crop. Peas, beans, alfalfa, birdsfoot trefoil, and

clovers are legumes which can provide a nitrogen credit.

Kacang Peas dan beans menyediakan kredit nitrogen 10 - 20 pounds per acre.

Alfalfa, birdsfoot trefoil, dan clovers memberikan kredit 30 - 50 pounds N per acre.



Pupuk kandang dalam tanah dapat menyediakan kredit N cukup besar.

Only a portion of the nitrogen in the manure would be mineralized

during the first growing season after application. This table

provides information on nitrogen credits for manure for the first

season after application. For example, if one ton of solid beef manure had been appplied over an acre the nitrogen credit would be 4

pounds nitrogen per acre.

Kalau 6,000 gallons pupuk kandang babi diberikan ke satu acre lahan, maka kredit N sebesar 66 pounds

(11 X 6 = 66).



Another material which can provide nitrogen credits to a field is sludge. Sludge does contain some nitrogen -- however, the nitrogen content

varies from batch to batch.

Annual sewage sludge applications should be limited by the amount of nitrogen required for crop

growth. You should test sludge for its nutrient content.

An important best management practice for nitrogen is to make sure that the fertilizer rate

applied is sound -- based on research.

Dosis pupuk N harus ditentukan berdasarkan kajian dan informasi ilmiah.



These fertilizer guides take into account the residual plant-available nitrogen in the soil profile, the amount of nitrogen that is

mineralized from organic matter during the growing season, the crop yield potential, and plant residue from the previous crop. The appropriate fertilizer guide for your crop of interest can be

obtained from your local county extension office.

BMP lainnya adalah waktu yang tepat aplikasi pupuk N. Waktu aplikasi yang tepat merupakan faktor penting yang menentukan

efisiensi serapan N – Efisiensi Nitrogen.

Strategi terbaik adalah aplikasi sebaghian besar N sebelum tanaman memerlukannya – bukan beberapa minggu berikutnya.



Waktu aplikasi pupuk N harus memperhatikan: 1. Aplikasi N musim hujan dan musim kemarau, 2. Aplikasi N sebelum tanam, 3. Aplikasi N secara ganda atau split, 4. Aplikasi N di sisi tanaman. 5. Strategi waktu aplikasi N tergantung pada pola pertumbuhan

tanaman.

Correct nitrogen fertilizer placement is another best management practice that can help protect water quality. The strategy is very simple -- put nitrogen in the vicinity of plant roots to maximize

nitrogen uptake and nitrogen use efficiency (NUE). The two most often employed placement strategies are banding

and broadcast placement.



Tugal (Banding) dan Sebar. “Banding” adalah penempatan pupuk pada

area yang sempit (band), liang tugal. The fertilizer is usually placed 2 to 5 inches below and to the side of the seed at planting.

In contrast, broadcast refers to a uniform placement of fertilizer.

Broadcast can occur either before or after planting. If before planting, it is uniformly applied to the soil surface and then mixed into the soil with an implement. If applied

after planting -- it is uniformly applied to the soil surface -- water is required to move the

fertilizer into the root zone.

Tanaman yang dipupuk dengan cara “banding” ternyata mempunyai akses

yang lebih baik terhadap pupuk.



Some advantages of banding fertilizer nitrogen compared to broadcast placement include:

An improvement in nitrogen use efficiency; you fertilize the crop to be grown -- not the weeds; the

nitrogen is close to the roots -- better chance of uptake; and the close proximity of the nitrogen

often improves early season crop growth.

Water management is a very important best management practice. Water management is a key

to groundwater protection.

Nitrogen dalam tanah bersifat mobil – ia bergerak dalam larutan tanah -- nitrogen dalam air irigasi

juga harus dianggap sebagai Kredit.



JADWAL IRIGASINitrogen is mobile in soils -- nitrate moves with water in the soil. Over-irrigation or excess precipitation results in nitrate leaching.

Nitrogen management alone will not effectively reduce nitrate leaching. You must couple it with irrigation/water management. To

protect groundwater, never over-irrigate.

Kredit NO3-N dalam Air Irigasi

Your irrigation water source may contain some nitrogen. Nitrogen present in irrigation water can be used by plants. Get your irrigation water source tested for its nitrogen content. If it contains nitrogen it has some fertilizer value. The nitrogen value of irrigation water can be calculated as follows: multiply the nitrogen concentration in the water by 1.35 by the number of acre feet of water applied. This gives you your nitrogen credit value. Many

surface water sources have some nitrogen content.



KREDIT NO3-N DALAM AIR IRIGASI

Your irrigation water source may contain some nitrogen. Nitrogen present in irrigation water can be used by plants. Get your irrigation water source tested for its nitrogen content. If it contains nitrogen it has some fertilizer value. The nitrogen value of irrigation water can be calculated as follows: multiply the nitrogen concentration in the water by 1.35 by the number of acre feet of water applied. This gives you your nitrogen credit value. Many

surface water sources have some nitrogen content.

Keunggulan pupuk N lambat tersedia (slow-release) : 1. Mereduksi pencucian nitrogen, 2. Mereduksi kerusakan gangguan garam pada kecambah, 3. Dapat memupuk N sekaligus – tidak aplikasi ganda4. Nitrogen tersedia pada saat dibutuhkan tanaman.



Nitrogen BMPsIf slow-release fertilizers have all these advantages -- then why doesn't everyone

use them? Probably because slow-release fertilizers also have one big disadvantage! Cost! On a pound of nitrogen basis, slow-release materials cost

between 35 and 40% more than traditional nitrogen sources. However, if nitrogen use efficiency (NUE) is substantially improved with a slow-release material -- its

cost may be competitive.

To show you how a slow-release fertilizer can be competitive let's look at an example: Let's say that under normal management -- 50% NUE -- you need to

apply 90 lbs of N. With a conventional N fertilizer -- let's say ammonium nitrate which costs $.30 per lb N. Using 90 lbs at $.30 per lb would cost $27.00 per acre. A slow-release material would cost more -- $.41 per lb N -- but it would also result in

high NUE -- 75% vs 50%. At 90 lbs per acre at $.41 per lb the cost would be $36.90 per acre.



NITROGEN BMPs

Bagian akhir dari BMP Nitrogen adalah pemilihan pergiliran tanaman dan pemilihan tanaman.

Pemilihan jenis tanaman dalam sistem rotasi mempengaruhi dinamika N dalam tanah.

Penggunaan tanaman penutup tanah juga sangat penting. Tanaman penutup tanah di antara tanaman pokok juga berfungsi menangkap kelebihan N dalam profil tanah.

Memilih kultivar terbaik untuk dapat memanfaatkan N-tanah secara efektif.

Documents

MK. Manajemen Kesuburan Tanah BEST MANAGEMENT PRACTICES Oleh : Prof.Dr.Ir.Soemarno,M.S