Impact Assessment for Agriculture
Preface

The Impact Assessment and Applications Section (IAAS) of Climatology and Agrometeorology Division (CAD) regularly issue this monthly/bulletin which will provide users such as food security managers, economic policy makers, agricultural statisticians and agricultural extension officials with qualitative information on the current and potential effects of climate and weather variability on rainfed crops, particularly rice and corn. This bulletin, entitled “Climate Impact Assessment for Agriculture in the Philippines”, represents a method for converting meteorological data into economic information that can be used as supplement to information from other available sources.

For example, an agricultural statistician or economist involved in crop production and yield forecast problems can combine the assessment with analysis from area survey results, reports on the occurrence of pests and diseases, farmers’ reports and other data sources.

The impact assessments are based on agroclimatic indices derived from historical rainfall data recorded for the period 1951 to the present. The indices, expressed in raw values percent of normals and percentile ranks, together with real time meteorological data (monthly rainfall, in percent of normal), percent of normal cumulative rainfall, as well as the occurrence of significant event such as typhoons, floods and droughts are the tools used in the assessment of crop performance. Crop reports from PAGASA field stations are also helpful.


The narrative impact assessment included in the bulletin depicts the regional performance of upland, 1st lowland and 2nd lowland palay; and dry and wet season corn crops, depending on the period or the season. Tabulated values of normal rainfall and generalized monsoon and yield moisture indices are provided for ready reference. Spatial analysis of rainfall, percent of normal rainfall and the generalized monsoon indices in percentile ranks are also presented on maps to help users visualize any unusual weather occurring during the period. The generalized monsoon indices in particular, are drought indicators; hence, the tables (see Appendices) together with the threshold values can be used in assessing drought impact, if there are any. It also helps assess any probable crop failure.

It is hoped therefore that this bulletin would help provide the decision-makers, planners and economist with timely and reliable early warning/information on climatic impact including the potential for subsistence food shortfalls, thereby enabling them to plan alternate cropping, if possible, food assistance strategies/mitigation measures to reduce the adverse impact of climate and eventually improve disaster preparedness.

Impact assessment for other principal crops such as sugarcane and coconut, for energy and for water resources management, are from time to time will be included in the forthcoming issues of this bulletin.


The IAAS of CAD will appreciate suggestions/comments from end-users and interested parties for the improvement of this bulletin.

Definition of Terms
The Generalized Monsoon Index (GMI) helps determine the performance of the rains during the season and serves as a good indicator of potential irrigation supplies. It is a tool used to assess rainfed crops.

The GMI for the southwest monsoon (GMIsw) in an area during June to September is defined as follows:
GMIsw = W6P6 + W7P7 + W8P8 + W9P9

The GMI for the northeast monsoon (GMIne) in an area during October to January is defined as:
GMIne = W10P10 + W11P11 + W12P12 + W1P1

where:

W = weight coefficient of monthly rainfall for the season;
P = rainfall amount in the ith month
(i = 1 for January, 2 = for February, etc.)

The Yield Moisture Index (YMI) is a simple index that helps the users assess agroclimatic crop conditions during the crop season. The YMI for a particular crop is defined as follows:
n YMI =  [Pi Ki] i

where:

i = crop stage (1 = planting/transplanting,
2 = vegetative, 3 = flowering, 4 = maturity, etc.)
n = total no. of crop stages;
P = rainfall during the ith crop stage; and
K = appropriate crop coefficient for the ith crop stage.

Tentatively, the threshold values of categories of indices for interpretation being adopted for both YMI and GMI are as follows:


PERCINTELE RANK INTERPRETATION
> 80 Potential for Flood Damage
41 - 80 Near normal to above-normal crop condition
21 - 40 Moderate drought impact with reduced yield
11 - 20 Drought impact with major yield losses
< 10 Severe drought impact with crop failure and potential food shortages

Agroclimatic / AGROCLIMATIC / CROP CONDITION ASSESSMENT FOR MAY 2020

OVERVIEW

Land preparation, planting and transplanting activities for upland 1st palay, lowland 1st palay and wet season corn had just started in CAR, Laoag, Basco Batanes, Tuguegarao, Munoz, Baler, Casiguran, Infanta, Tayabas, Legaspi, Virac, Catarman, Catbalogan, Malaybalay, Davao Region, Surigao del Sur and ARMM because of sufficient moisture available in those areas. Contrastingly, any farming activity related to planting rice and corn might be hampered in Vigan, Dagupan, Aparri, Zambales, Calapan, Romblon, Masbate, Panay Island, Region VII, Tacloban, Region IX, Misamis Oriental, Surigao del Norte and SOCCSARGEN due to the inadequate moisture received in those areas. Standing corn crops in Catanduanes and Surigao del sur are in good crops condition, while in Camarines Norte and Surigao del Norte, crops suffered moisture stress.

The weather systems that affected the country during the month were the Northeasterly surface windflow, ridge of High-Pressure Areas (HPAs), low pressure areas (LPAs), Intertropical Convergence Zone (ITCZ), Tyhpoon (TY) Ambo, easterlies and localized thunderstorm. A persisting warm ENSO-neutral condition has also been observed and is forecasted to continue until the third quarter (July-September) 2020 based on climate models.

REGIONS

Land preparation, planting and transplanting activities for planting upland 1st palay as well as wet season corn had just started in Laoag; this is due to the ample amount of moisture available in the area. In contrast, other parts of the region received very low rainfall during the month which hampers all farming activities.
Land preparation, planting and transplanting activities for planting upland 1st palay and wet season corn had just commenced in Batanes and Tuguegarao, since the rainfall amount had been sufficient during the month. Meanwhile, in Aparri, due to very low moisture available in the area, planting activities for rice and corn are hindered.
Sufficient moisture was available during the month which favors land preparation, planting and transplanting activities for wet season corn as well as upland 1st palay across the region.
Land preparation, planting and transplanting activities for upland 1st palay and wet season corn had just begun in most parts of the region, except in Zambales. This is due to the lesser amount of rainfall available in the area during the month.
Land preparation, planting and transplanting activities for planting wet season corn and upland 1st palay had just started in Tayabas, and lowland ist palay in Infanta. It is because of sufficient moisture available in those areas,
During the month, land preparation for wet season corn as well as upland 1st palay cannot be done in either Calapan or Romblon; it is due to inadequate rainfall received in those areas during the month.
Inadequate rainfall received in Masbate during the month hindered any farming activity related to rice and corn. On the other hand, sufficient moisture available during the month favors land preparation, planting and transplanting activities for planting wet season corn and upland 1st palay in Albay and Catanduanes. Meanwhile in Camarines Norte, insufficient moisture available hindered any farming activity related to planting wet season corn. Standing dry season corn in the area might have also suffered from moisture stress.
Insufficient moisture available during the month hampered all farming activities related to planting rice and corn across the region.
Inadequate rainfall received during the month hampered any farming all activities throughout the region.
Land preparation, planting and transplanting activities for planting upland 1st palay and wet season corn had just started in Catbalogan and lowland 1st palay in Catarman. It is because of sufficient moisture available in the area, while in Tacloban, farming activities are hindered by inadequate rainfall received.
Insufficient moisture available across the region made it impossible to undertake any farming activity related to planting rice and corn during the month.
Due to adequate moisture available during the month, land preparation, planting and transplanting activities for upland 1st palay as well as wet season corn had just begun in Bukidnon. On the other hand, in Misamis Oriental, all farming activity related to planting rice and corn may be hampered due to the minimal rainfall amount received.
The ample amount of rainfall received during the month favors land preparation, planting and transplanting activities for planting wet season corn, as well as upland 1st palay, across the region.
Due to very low rainfall received in all parts of the region, the planting of rice and corn is hampered.
Sufficient moisture available during the month favors land preparation, planting and transplanting activities for wet season corn as well as lowland 1st palay in Surigao del Sur, while in Surigao del Norte, planting of rice and corn might be hampered because of lesser amount of rainfall received in the area. Likewise, the standing dry season corn in Surigao del Sur is faring well, while in Surigao del Norte, corn crops suffered moisture stress.
During the month, land preparation, planting and transplanting activities was favored by the ample amount of rainfall received across the region.

Ten Day Rainfall Distribution

Monthly Rainfall Distribution

Generalized Moonsoon Index

Tropical Cyclone

Actual Rainfall and Potential Evapotranspiration

Stations

For Particulars, please contact:

THELMA A. CINCO


Impact Assessment and Applications Section (IAAS)

Climatology and Agrometeorology Division (CAD)

PAGASA-DOST

Telefax No.: 434-58-82